Discussion about the Korg PolySix synthesizer

I finally had the chance to start taking apart my PolySix.  It needs 
a good cleaning on the inside, and I find a 4 of Diamonds playing 
card underneath one of the PC boards.

The KLM-367 board has prior to been worked on.  Underneath there are 
some wires patched into IC-31. I don't think whomever did the work 
cleaned the PC board too well as a lot of the solder points on the 
top of the board in the area above the battery all the way up to the 
connectors suffer from corrosion. This board is beyond my ability to 
repair; I am neither knowledgable enough or disciplined enough to do 
it.  I would consider myself an artist who can maintain his gear 
rather than a technician with an affinity for music and/or 
synthesizers.

Many questions have I:

Should the pitch bend wheel have springs?  I noticed it wasn't 
springing back when I first got it, but I didn't think much of it 
figuring the springs were unhooked or stretched or something.  If it 
should have springs, can anyone recommend a replacement?  If it came 
from the factory spring-less, has anyone tried adding springs?

I'm far from wealthy, I'm hardly even middle class, so my resources 
are rather limited.  I want the PolySix to come alive, however once 
it's alive I want to be as certain as possible I won't have to invest 
more money into it for many years.  The question is, will replacing 
KLM-367 fix the other significant problems it has: waveform selector 
not working, the two patch buttons and two program buttons always 
staying lit?  

I'm not asking anyone to make decisions for me here, it would simply 
be very helpful to have some insight on the KLM-367 matter so I know 
where I'm at. To be quite honest, I'm now trying to decide whether I 
invest money in it now, or cut my losses and sell it as is (and, 
unfortunately, another synth) and get something more reliable like a 
Juno.  For what I'm doing musically, I need the knobs (or sliders).

So, please, any thoughts would be helpful.