My Sony TCM-100 occasionally dislatched the play button half a second after I press it. I opened it up thinking it was a faulty latch but in the attached image I've encircled 2 plastic parts that, as far as I can tell, aren't loose, broken, or misplaced. The white part on the right seems to occasionally push the black part on the left far enough to disengage the play button, but other than that it doesn't do anything other than slightly touching the black part which doesn't do anything. I'm curious if this is intentional, maybe something to do with the tape counter. If it is, then I want to know what happens if I cut off the black part so the white part can't push it to disengage playback.
Ok, first of all leave that black part alone don't cut it as it's part of the auto-stop mechanism. Please check the operation of the auto-stop mechanism: it's described in detail at page 3 of the attached TCM-600 service manual. Does that white lever move up and down in tandem with the cam gear ?
Here is a demonstration I uploaded to YouTube: In this video the unit is first playing as normal, this is to demonstrate how the plastic pieces subtly touch each other but not in a way that would wear them down or cause the dislatch. I eventually press the stop button and then press play, but half a second later the white plastic piece on the right is aligned in such a way that it pushes the black piece on the left far enough to disengage playback, because the black piece is connected to the latch of the play button.
Think I have spotted what the problem is: the detection lever has a spring that seems not hooked on one end. Check attached picture. So leave that black part alone, that's not what's causing the problem. Those 2 parts are supposed to touch, that's by design.