Vintage Synth Repair

Dear All , 

Hello :>)

Hope I have come to the right place, have spent hours looking at 
sites for Roland, with patches and very techical stuff on, but 
nothing abut physical repair of electric pianos.

I have recently bought a Roland EP20 on Ebay, having wantd to learn 
to play the piano for years and this was very cheap,a good make and 
retro, so a bit cool.Heavy too! Choice of about 2 sounds so no PC 
required for this one.

It was sold as having some keys not working, fair enough and about 10 
out of 49 don't, some being muted, some silent and some a sort of 
static noise.
The duff keys  don't seem to follow any pattern either, being 2 apart 
then 10 apart then together etc

I took the back off and to be honest, it was way more technical than 
I had imagined! As it was a 70's? instrument, I was expecting 49 
keys, 49 switches to clean. Please don't laugh at me too much....

If necessary, I will send it to a repair shop but am itching to start 
playing right now and "entertain" my kids over Christmas.

Are there any simple steps that I could try, such as cleaning 
solutions etc or ways of testing contacts. I have had a look at the 
innards and there are no broken wires or burnt out circuits.
Too complicated stuff is a no-no as I fear my sausage fingers would 
not be up to replacing diodes / transistors in a circuit board.

Any advice gratefully received

Patrick
Chester , England