what to do with a stereo that needs repair

I have a relative studying electrical engineering in College and one of their courses is amplifiers. He fixed several items for me. They weren’t high end like your item but amplifiers nevertheless, and it was fun for him, he at least knew enough not to make it worse but at the end he fixed it. My point is, it may have a simple issue and it may be easier to find someone to repair than it might seem. If you are stuck with it/couldn’t sell it as it is, the risk is reasonable too.

Have you checked the fuse(s)? Looked at the solder on your input jacks and speaker post connections?

Touch the tubes - carefully. Is there any heat in the small tubes, the power tubes? 

Swap the tubes left to right and vice versa. Is the same channel is still dead?

Unplug the amp, IMPORTANT!
Remove the bottom and see if there are any obvious wiring faults, Look at the speaker and input connectors. Do you any burn spots on the solder points? Charred resistor? caps(s)?

Single-ended class A Tube power amps are not very complicated pieces to repair.
They run very hot so there is a possibility a relatively inexpensive part might have failed from heat.   

You may be able to fix it yourself.

Nice amp get it fixed, Try to find a qualifier local tech

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Invariably you should recover your costs in having the amplifier repaired should you decide to sell upon return , you will achieve a much better price for a working amplifier and it will be easier to find a buyer.