Yashica 635 Copal MXV Shutter

I have just purchased a Yashica 635 TLR but it has an issue with the self timer mechanism. It is working of sorts but not as intended. The actuation lever moves only a short distance so that cocking the shutter and and the self timer (which only moves partway) then firing the shutter the maximum delay is about 3 seconds then the shutter fires. It all appears to function correctly except the time delay is shorter than it should be. Now I have not dismantled anything as yet but looking into the slot that the timer actuation lever moves in it has a steel part stopping it's travel. I have found on the Internet some images of this type of mechanism dismantled. From these images I have identified the part. Can anyone help with function of this part and why it would interfere with the timer actuation lever. The part is arrowed in the image.

Identification of the Arrowed Component​

Component is (functional):​

Self-timer blocking / release slide
(often also called the self-timer interlock bar or timer release slide)


This is not part of the shutter timing train itself.
It is part of the interlock between the self-timer and the shutter

What This Part Does (Critical)

This sliding bar has three jobs:

When the self-timer is set

It moves into the shutter release path

It blocks the normal shutter release lever

It forces the shutter to be fired only by the self-timer

During the self-timer countdown

It is held under spring tension

It slides gradually under control of the timer train

At the very end of the countdown

It moves just far enough to trip the shutter release

Immediately after firing, it must:

Snap fully back to its rest position

Completely clear the shutter release path

If it does not return 100%, the shutter will not fire normally.

Don't know where you got that description from but it's mostly totally incorrect.

The part you arrowed is there to PREVENT the self timer from being set if the shutter is in M mode. The self timer should ONLY be used with the shutter in X mode otherwise the self timer can be damaged. If you move the X/M switch you will see the part gets moved upwards into the path of the self timer lever to STOP the self timer being used. Unfortunately, few people bother to read the manual and just force the self timer past the lock resulting in, usually, permanent damage. Yours looks undamaged (so far) so try and keep it that way.

EDIT: Just realised the picture you posted isn't yours so yours may already be damaged.

Here's one that's been forced.