Something that may help all you folks out there who are having intermittent problems with your CDR-23 Systems.
When for the 3rd time, my RH channel stopped working, I decided to take out the amp and see whether I could fix it. On opening it up I found a number of dry solder joints - this is where (usually through heat) the solder around the component wire has cracked.
I got out my trusty Weller solder station and soldered up all the joints that looked suspect. Hey presto - amp working perfectly again.
It's my guess that the power transistors get quite hot and over time bad connections will develop.
Happy to help anyone who lives in the Kent (United Kingdom) area.
Let me know if this works for you.