Hey all, I stumbled upon this forum while trying to research repair options for an M70 I found last week at an estate sale.  The thing was sounding perfect when I first brought it home and then, while playing music from my desktop via the 'line-in', it just started going all distorted.  It sounds OK when you have the volumes sliders barely up (say on level one).  But, past that, it sounds awful and causes the red power indicator light to pulse, like it's clipping or something.  Both sides and all speakers seem to be experiencing the same problems, so I don't think it's isolated to just one woofer or tweeter.  Also, it lost its ability to pick up any radio channels.  There is just a low hum emitted where it used to clearly pick up an FM channel. 

Just prior to this, the circuit it was plugged into (in the wall), was blown as a result of the electric stove and range both being on...this is a new apartment for me and I am learning of its pitfalls and problems.   My PC and all computer gear was plugged into the same outlet and they aren't damaged, but I thought the incident was worth mentioning.

If I had to guess, I'd say it had been sitting, unused, for many years before I came to own it.  Also, I wasn't cranking it or anything, it was just on a low, listening level, playing some Glenn Gould piano sonatas (...I'm a party animal, I know).

Any pointers or advice on repair options?  I took the back off and the only thing I could see that I could actually service was the fuse.  But, if the fuse was bad, it wouldn't power on at all, right? I live in D.C. if someone knows of a repair shop here, I'd be all over it. 
Thanks, awesome site y'all have got here.