I have ds125 with serial number 11xxx. On my last trip I encountered problems with unexpected strobe firing which progressed at times to rapid firing. I have read on Ikelite's site this is usually the sync cord. I also noted once the unit was powered on, an occasional high pitched beep after the inital warm up. I don't recall this beep in the past. Is this normal or am I hypersensitive since the rapid fire issue? Since my strobe has been well traveled, I replaced the cord, appears the random strobe firing problem is solved but the high pitch beep is still there. Any thoughts?