I owned that same amp. I had the same problem as you. I emailed them and got the following response:
look at the picture, this is the inside of the SA-200.2 looking at (1)
amp module. You will see I have circle (3) wires connected to the PCB
pink. Disregard the circle in red because it doesn't apply. We have
learned the manufacture of these connectors used oil film coating on
them for storage
the connector are plugged into the board sometimes the metal doesn't
make a good connection. To make a better connection we would pull the
and push back on once or twice. By pulling off the connector and
pushing back on the (2) metal pieces scrape and dig into each other
making a very good connection.
There are (2) amp modules. So one would have to do this for both channels."
I did what they suggested. It did not resolve the problem. I ended up selling the amp. Cary Audio is not the company it used to be. While I still use a Cary SLP-98P preamp, I certainly would not buy a new product from them.