Hi All, new to the group here, have a question about my oberheim matrix 1000. I purchased this a few years back on ebay, powered it up and had a quick listen and initially thought it was ok functionally and amazing sounding. Once I played around with it a bit I could see I had some dead voices and some funny behaviour. Was busy at the time so didn't get a chance to try and fix it until recently. 

So I opened it up and was struck immediately that an IC had been removed, being the optimist that I am I thought maybe this is just a design quirk. So I replaced some of the voice chips but still no luck, limited polyphony, some voices(1) don't appear to be triggered at all and on some voices I get noise instead of notes occasionally. 

So I went back to the chip that was missing and on inspection could see that a chip had in fact been removed. The area on the circuit board is U802 and it looks as though the chip was an M27256 which seems to have been an eprom. There is another of these present on the board, anyone know if this is my problem (I'm fairly sure it must be ), can I get a replacement and would I have to program it

Any help greater appreciated, I really want to get this synth going. I finally have the time and facilities to start recording some music and think this synth would be extremely beneficial to me.