Well, I've just finished the first film I'd put in my '57 ambi silette, and my suspicions were correct, the shutter has practically died. It started off "a bit too quiet" a lot of the time (as mentioned in a previous post), today the opening of the shutter started happening well after the button was pressed, so after I took the film out I fired through the speeds and noticed it was mostly either late in firing or not firing after the first or second wind-on. Out of curiosity I moved the switch to 'M' and while the shutter was still firing late, I could sometimes get it to fire at 1/8 and 1/15! I moved the switch to 'V' but the the self timer only worked after I'd switched back to 'X'. Now the shutter doesn't open most of the time.
I don't know whether to bother getting the film processed.