A great analog subtractive synth with 'memory' which amounts to miniature versions of the non-global parameter sliders X4, and presets with typical old school technology. Just a lot of it! Nice Ring mod and overall filter adjustments and the classic pitch ribbon controller! Check out Crow's page on the VCO here
Typical problems in CS series are power supply over voltages which blow tantalum capacitors and they short, or the caps just fail over the years. During this various chips may be taken out. I've seen LFO chip, VCA's and dac comparator fail so they might be most susceptable. In the CS-80 many other things happen. Definitely check out Old Crow's site for a great overview.
I had a most peculiar manifestation shown in a video I did on CS5. The cutoff control would just cease to impact a highly filtered sound at the Ab second from top and below or like that. It would change a note during warmup. Turned out the VCF chip was the issue!
ALso the touch strip may be rusted inside and I've seen spring on YC45D that just fell into small pieces! Fortunately it looks like a chap in UK has a precise spring replacement. He wants about 160 pounds to refurb it. The springs I got from McMaster Carr weren't quite right in diameter and I had to monkey around trying to make an actuating spacer that worked well enough I guess but if you have this issue you may want to contact him (Tom Szakaly) at email@example.com .
Slider caps and Knobs- I have a decent selection of rotary knobs (Contact Sound Doctorin') and check Synthparts.com for slider caps.
Semiconductor and Parts:
See Semiconductor page. I believe I should have any electronic part or keys for these save exact transformer, etc. Ask if you have need.
Contact Sound Doctorin'