Vintage Synth Repair

Hi
Im new to this group...
Ive got an MS-20 which was working fine when i bought it,  but has  
recently had a few functions fail on me. I was hoping people might  
have had similar experiences/ and or might be able to point me in the  
right direction because unfortunately in Sydney, where I live, analog  
synth repairers  are either hard to find, or totally untrustworthy.
(If anyone knows a good one - let me know please!)

I'll try to give a detailed explanation of the problems:

The keyboard was working normally and has now stopped working. It  
worked sporadically one day, then stopped all together.  I can still  
still trigger the VCOs via CV/midi. When I press a key it still  
lights the EG2 LED as well..so Im thinking all is not lost for the  
keyboard. I took the synth apart and did some rudimentary resistance  
checks with a multi-meter along the keyboard - it all looks fine -  
its when it attaches to the main circuit board that I get lost and  
dont  know what to check

Also in the patching section the HPF and LPF patch points don't seem  
to work anymore, along with a few other patch points....I'd love to  
get this working again. The filters themselves work fine, just not  
the patching. I know it worked when I bought it, and then just  
stopped. Ive looked over the circuit board for dry solder joints too,  
but I stopped there. (I didn't find any)


Apart from that , the machine works well - I love it.:)

Thanks for reading this.
Any thoughts would be greatly appreciated.

R.