Sherwood Receivers An Inexpensive Surprise - Sherwood Rx-4109 How Can I Repair A Sherwood Receiver?

How can I repair a Sherwood Receiver? - sherwood receivers an inexpensive surprise - sherwood rx-4109

I have a Sherwood receiver S2620CP. The left channel is shut down temporarily on. I sprayed contact cleaner on both the volume control and adjusting the balance. This has not helped. Could a faulty component on the motherboard or should I replace the regulator to balance? Other ideas?