Parasound A23 working point adjustment

Hello dear diyAudio members!

I would like to ask for help with a Parasound A23 amplifier. The phenomenon is that one, the left side when in use, is very hot, while the right side heatsink, channels cold.
I assume that working point could be set.
I have no schematic diagram, maybe someone can help with this, even just a detail of where to start?
Or a service manual where I could possibly start based on measurements?
Thanks in advanced.
Br,
Csaba