I've owned numerous Counterpoint amps, preamps including a SA-220 which is a more current version of the SA-20.
I've moved on from this gear.
The Counterpoint amps were known for mosfet failure of which the replacement parts are no longer available. Sometimes Mr. Elliott has some used mosfet parts he salvages when he performs rebuilds/upgrades. Or, you can opt for a rebuild/upgrade which is pricey IMO.
My brother once purchased a Elloitt modded SA-220 here on Agon. The Fedex shippers had their fun with it so I was damaged. Elliott inspected the unit and replaced one medium size cap. That repair bill was almost $400 not including shipping. My brother packed the amp in another box (since the original box was ruined) and secured the amp with foamy peanuts. Elliott charged $12 to pick up the foamy peanuts off his shipping/receiving floor.
A crazy but true story. The face plate was severally bent and these are near impossible to find used. Also, if you decide to get the amp fixed locally Elloit charges, if I recall correctly, $75 for a schematic. These schematics reflect original circuit design. His modded preamps/amps used a different circuit layout so the original schematic is not usable. Your then stuck shipping the modded unit back to him for repairs which can be costly.
Do NOT ship the amp to him.
Post it here on Agon. Some Agon member/techie may buy it who has the ability to repair it. Move on and get something else. Else, be prepared to pay serious money.