Need help with s600 purge cover replacement

[landlockeddivingdoc]

Hi all. At my wife's request, a lot of her gear is getting accessorized in pink... Including her primary, a 4th Gen scubapro s600.

Today I swapped out her mouthpiece easily, and I tried to swap the purge cover, and am running into a problem:

-retaining pin removed without issue

-faceplate/old cover were snug, but not so much that I couldn't twist them off using only my palm

-faceplate, cover, antifriction assembly look fine. Diaphragm looks fine.

-parts were cleaned, dried. New cover placed in faceplate, making sure the little tabs were in their respective places, and cover sat flush.

-parts were reassembled, ensuring no cross threading, and I attempted to screw it down, and this is where I'm getting into trouble: I can't seem (at least with palm pressure) to rotate it the last 1/8 of a turn to get it into alignment/permit replacement of the retaining pin.

Although I'm probably just overthinking this and just need to force it one way or another, I'm reluctant to do this because it looks like the little silicone struts (that run from the button to the base ring) on the purge cover are quite asymmetric at the end of the installation attempt relative to their position in the apertures on the faceplate-the best way that I can describe it if it's not very visible in the picture above (it's quite noticible in person), is that the pink "strut" seems to "drag behind" the chrome struts on the cover as it's being screwed clockwise. and this makes me worried that instead of just compressing, it's being subject to quite a bit of rotational force when being screwed down. ..And I'm worried about the damage or functional implications if that holds true of the diaphragm as well.

What am I missing here? Do I need to just get a tool and force it? Put some christolube on it? Exchange the cover?

Any advice would be greatly appreciated.

 

[Nemrod]

I would not recommend putting silicone on the diaphragm to case seal. Silicone could cause the parts to slip out flooding the second stage. Most likely there is a minor difference in thickness of the new cover and old.

I assume that if you did a test fit with the old cover that the case regains alignment?

If so then wet the parts and then see if you can get alignment.

Use a soft jar opener, set it on your counter. Press the face of the second stage into the jar opener and twist with your weight pressing down as you twist. Do not over do it.

 

[Tanks A Lot]

Your concern about rotational forces being applied especially to the main diaphragm is absolutely well founded, one that ScubaPro put quite a bit of thought into as well.

1. Part #18 (11.602.035), the anti-friction washer has a little tab that slides into the housing. This tab will prevent this ring from turning when the purge cover is screwed down. This eliminates any possibility of rotational forces being applied to the diaphragm itself.
2. On top of part #18 sits part #19 (11.600.050). This ring acts as another anti-friction ring, preventing any rotational forces from screwing down the purge cover acting on the anti-friction ring above the diaphragm.

Looking at pictures is always hard, but a couple of things come to my mind:

• From the pictures I'm missing part #19 (11.600.050), which acts as an anti friction ring. If this ring is missing your shiny new pink purge cover will come into direct contact with part #18. As the silicone is fairly sticky, it will get stuck on part #18 when screwed down. Check your old black purge cover, these white rings love to stick to the purge covers. It may very well still be there.
  The resulting friction from the missing slip ring #19 is getting to much for you to overcome by hand. I would not tighten it any further, as you'll probably damage the new purge cover. Either the tabs get bend, or you score the lower surface.
• The purge cover #20 (11.602.036) itself has 8 little tabs which need to get aligned correctly with the corresponding slots in the ring #42 (11.603.137). 1 out of these 8 tabs is a little bit smaller than rest of them. Could it be that you accidentally inverted the cover by 180°? This would let the cover slip out of the slots much quicker, as one of the big slots didn't fit into the small slot.
  I do doubt that this is the case here, your picture looks to me like you aligned the small tab with the small slot. Then again, I find it hard to say these things from pictures alone.
• If both of the above are not applicable, it is likely that you are too gentle with the parts. Especially new purge covers tend to be harder to install. A cover that has been in use before, sat a lot of time sandwiched between those parts and will to a certain degree deform and make it easier on re-installation.
  More torque would be the obvious answer here.

When installing these covers, especially older, damaged ones, I like to take a long barbecue skewer or similar as an aid. Install the purge cover #20 into the ring #42. Now thread the skewer through the aperture on the ring and cover on one side, continue underneath the purge cover and thread it out through the opposing apertures. Do so only with the purge cover and ring, before you start screwing it into the main housing. Doing so while having things half assembled may risk poking a whole into the diaphragm.
Now leave the skewer in there and start screwing the whole thing into your housing. As soon as the purge cover makes contact with the anti-friction rings, you can remove it.
Having a skewer in place helps tremendously to keep the tabs inside the slots where they should be. Granted, this should not be an issue with new purge covers, but is quite often a pain in the ass with older ones.

I would advise against using any kind of grease on the cover. As Nemrod said, this will make the purge cover rather slip out than anything else. There really shouldn't be any rotational forces if the anti-friction rings are all in place. It will not result in flooding, unless the diaphragm gets dislodged as well.

 

[landlockeddivingdoc]

Thanks to both of you for your replies--I'll certainly add the wetting and using a soft jar opener to my toolkit.

I looked at my parts again, and everywhere around my workspace, and can't find #19 (slip ring) anywhere. I kind of suspected this when I compared it to the maintenance manual, but tried to rationalize it due to the various design iterations (your forwarded schematic is MUCH better and higher quality than what I have to work with.

Also, I the tab on the anti-friction washer doesn't have sufficient purchase--its a little nub, and (if I'm looking at the correct placement, photos below), barely sits in the (nondamaged/nonoccluded) slot in the body--it can get dislodged with just the play of moving the ring back and forth while it sits in the case. It doesn't look sheared off, but rather worn, though I'm not sure a nonmoving part should wear like that.

In any event, I'm going to take it into a new LDS to have it gone over--the above seem like easy fixes, but I'm concerned if there's actually an entire piece missing, because it was just serviced late last spring/winter (although to be fair, it doesn't seem like there are any functional issues), and I would feel better with having a set of trained eyes double check the servicing that was done and the general condition.

In my line of work, if you don't do it yourself you assume that it wasn't done properly, and unfortunately that extends to nearly the point of OCD with professional service delegation (home repair, auto repair) and I might have to add regulator servicing to that list. I've been doing "cosmetic" and easier fixes, and am on the waitlist for Robert Singler's regulator service course. Hopefully that'll give me a bit more skill in looking at problems like this, and ultimately better confidence in my gear.

 

[Tanks A Lot]

That tab of the anti-friction washer clearly broke off. It is much longer on an undamaged piece, which will definitely prevent it from rotating.

How it broke off is of course anyone's guess. The most obvious answer would be an overzealous technician, placing it wrong.

 

[Nemrod]

I guess I need new glasses, I thought I saw the slip washer in that photo. Yes, indeed, if you are missing your slip washer by all means get another. It is not an optional part if specified on the PL.

Some SP regulators, at least the standard version of the G260, have a built in slip washer integral to the cover. Unless you get the carbon fiber G260 model and it has a separate slip washer.