[sdiy] Keyboard Connections

[med]

Okay, I've got myself an old Thomas organ (lemme tell you, if you've
got a forklift or a few strong men and a Huge-Backed Truck you can
pick up an organ real cheap or even free in the classifieds!) whose
manuals ("keyboards") have a bit of an issue.

Some of the keys on the lower manual tend to make only intermittant
contact, and that only if you press it forcefully. It wasn't played
for a long time, and presumably, this led to something accumulating
there. We immediately wiped down the organ with various towels when we
first got it to get rid of the surface dust, and I opened it up to
vacuum it out, and retuned the three oscillators that had gone flat.
(odd side note: The various notes are generated by one of 12
oscillators. Does it divide the frequency down for whatever octaves it
needs and then add harmonics for whatever stops it is using?)
On the upper manual, there are various sounds you can patch in (i.e.
8' whatnot, 16' whatnot, 4' whatnots) and when you press some of these
keys it again, the higher sounds come out clearly, but the lower notes
(i.e. the regular note and the octave below it) make intermittent
contact (kind of a sputtering of the notes, and sometimes they just
don't 'come on').

I've opened it up, and it has a (what i believe to be called) matrix
type action, where pressing a key moves a little metal wire which
touches a grid. I'm assuming that in the twenty years (!) that it was
not often played, some dust and 'crud' accumulated there. The only
problem is that this 'matrix' is directly over the sound-generation
circuitry, and if i spray contact-cleaner there (my first idea) it
will drip onto the components. Since you guys seem to do a good job
self-repairing old synths, perhaps you have had to deal with this
issue? What do you recommend? Is this even the correct means of
tackling this issue?