coca cola... bad news.
The 651 center section: -Remove all the cards. clean the mother board.
Keyboard- no schematic that I've a recollection of having seen... Replace the whole module if you can't clean it. replace switches
Remove and clean the master fader if it needs it but...
BEWARE of disturbing the 651 top panel. It's a mater-work of hand-wiring. If you have to "peel it back" (which is done using the wires at the right as a 'hinge' be VERY careful. I DO NOT do this unless it is absolutely essential. You run the risk of doing a lot more harm than good, since the wire is all solid, usually very old and brittle.
It is usually a miracle if everything works after you attempt this. I strongly urge you to NOT try this yourself, find someone who does this for a living and have them do it for you. Make sure that they can fix what they break, because they will almost certainly break things.
Sorry, but that was an expensive can of coca cola!