ok, so the cct is on all the time, (the battery wont last long)
there's nothing else thats been changed, its a strange one. I've known the tone pump is Spectors to die but never in a MM...
hmmm.
The possibilities are pretty large at this point, its its still more likely than not to be something simple. A stray ground lead, or short cct somewhere etc.
There isnt much i can say apart from visual checking. If you could get a signal generator on it and follow through the cct test points and monitor the signal size and shape with a cro you'd find it pretty sharpish. With this type of cct its usually just standard mechanical failures, shorts etc.
i'd be tempted to take the whole thing out and let anything unwanted fall out (stray washers etc) and keep testing it. With this kind of thing it usually just suddenly works and you notice a small shiny culprit lieing on the bench.
Sorry I cant help more, good luck
