st way to check crystal sync
would be with a timing strobe light set at 24 f.p.s (flashes per second=frames
per second in this case) The light is aimed toward a moving object inside the
camera, sprocket wheel, or claw or registration pin. If the camera is in sync
basically it will look like the movement if frozen, if sync is off youll be
able to see some movement. Using a strobing mechanism is a hell of a lot easier, accurate, and
inexpensive than what you had originally proposed.
You can have your timing (amongst other things) checked by a trained
technician at a reputable service house or the alternative would be to get
yourself a strobe to check the timing yourself--only thing is , say you find
out that the timing is off...will you be able to fix it?? Best bet...see your
local camera doctor on this one.