http://webpages.charter.net/coinopcauldron/Index.html he has fixed many boards for me super company,but if your board has a lot of corosin.i would buy a new one,just my thought why spend 100 to fix a 30 year old board when for 200 you can have a new clean updated one.
Is there corrosion? The third flash is the 5101 RAM. If there's no corrosion I would suggest replacing that RAM and possibly the socket. If there's corrosion you might want to have it repaired or consider a new board.