I do have the schematics but had trouble with my scanner so I'll need to deal with that first. Since there is some interest in copies of these, I'll make scanning the schematics a bad weather project. I certainly support making these available.
My manual covers the MTR-10II and MTR-12II and there are separate schematics for the 4 and 2 track models where they vary (eg the meter bridge). The schematics are printed on thin paper and some of them have torn loose from the binder so, as I said before, I'm not sure I have the complete set. I've seen other manuals where all the schematics were missing. I suspect that an engineer may have purposely removed them from the manual to keep them safely on file or perhaps to keep them away from someone in the studio who damaged other equipment.
Mark - if you lost the lights to your VU meters at the same time as the LEDs, I wonder if your 7.5 VDC supply is out (maybe it's 7 VDC, I'm at work and the schematics are at home). I had to replace those bulbs and as I recall they are connected between 7 VDC and ground without any switches or other circuitry in between. I'll scan the relevant schematics for you a soon as I can.