Ultimate stereo nightmare

OP. I would next evaluate your amp if your pre IS working ok.

Play some music by sending the signal directly into the amp (bypassing the pre) using a CD player, streamer, etc. and see if both channels are working. If the right channel is still not working switch the speaker wire and see if the problem lies in your amp or speaker wires.

Bruce

 After seeing your system, here are some suggestions for the technician:

1. Remove the TV from the table top,

2. Put some plastic slider discs under the 4 table legs (found at home depot),

3. Use a couple of belts to wrap around the very bottom of the front table legs,

4. Grab the belts and SLOWLY pull the table away from the wall (may take 2 people),

Note: Disconnect your speaker wire before moving the table (if possible).

This should provide plenty of work room.

Good luck!

I have a really stupid suggestion and I am not in any way making any type of comment on one's intelligence or technical capability.  I know a guy whose left channel went out on a brand new, not inexpensive, McIntosh setup.  He was kinda pissed and laid into the dealer who kept telling him this isn't possible.  My friend changed the cables from one channel to the other and confirmed the left one was not working. 

After a bunch of back and forth, the dealer paid a house call to see the problem for himself.  He took the remote, pushed buttons to get to the channel balance function, saw it was 100% over to the right channel, rebalanced for both channels and WOW!  music came out of both channels.   Kind of embarrassing, to my friend 😯

Have you checked your channel balance function?  May save you a house call cost 😏

If you lived in Connecticut, I would gladly come out to help. I stay away from Long Island due to all the traffic. I’m willing to bet a cable pulled away slightly from one of the pieces of equipment and won’t make contact.  I get what you say about getting down on the floor.  I got a new OLED TV last Saturday and once I got on the floor to monkey with the cables, I couldn’t get back up.  I had to call my wife for assistance.  

1. Roll on your stomach,

2. Get on your knees with your hands on the floor underneath your shoulders,

3. Drag your right foot forward until it’s on the floor,

4. Be next to a table or dresser and put your arm on its top (you can also use your knee to boost yourself up).

5. Should be able to wrangle yourself up.

P.S. I have an adjustable metal cane that comes in handy for this kind of activity.

It’s all technique!