My compur-P shutter works fine on M-SYNC, but will not open when set to X-SYNC. Is this an easy fix? (If I'm handy, should I even think about popping the cover to take a peek inside?) Alternately, If I wanted to use electronic flash, could I use M-SYNC and a simple delay circuit to fire the flash X mSec later. How big is that delay?

That's odd! If the synchronization mechanism is going to impair the operation of the shutter, you'd expect it to happen when the timing-gears are engaged for M or F synch.

These things often (not always) are occasioned by the buildup of crud in the timing mechanism over the ages, and cleaning usually (not always) can resolve them.

The M synch setting, by convention, closes the flash circuit to fire the bulb 30 milliseconds before the blades open fully.

Opening a blade shutter is not for the faint of heart, but if you have the time and the small tools, and you proceed methodically in a well-lit work area designed to permit easy location and recovery of errant parts, it's not all that bad.

Thanks for the response. I think I'll at least open it to see if there is anything obvious. I post back when I have more info...