Left rear & main speakers are not working

SOURCE: no sound to right speaker

It's probably just a cable problem. Reconnect the RCA cable from the receiver to the right speaker and even try to replace the cable. Good luck.

SOURCE: Left front main speaker level drops after being on for a few hours

Run the speaker test mode :

While running the speaker test tone to balance your speakers, you cannot adjust the balance of the Main speakers independently. The speaker test allows you to balance the sound (dB) levels of the Center speaker, Rear Left, Rear Right speakers to match the level of the main speakers. So, the first thing you do is press the [TEST] button on the remote. Next, adjust the [MASTER VOLUME CONTROL] until you can adequately hear the level from the main left and right speakers. Then, as the tone travels clockwise to each speaker, listen carefully from your main seating position in the room to determine which speakers (if any) need to be adjusted in level (either up or down) in order to balanced the sound to the main speakers output. Then adjust the Center, Rear Left or Rear Right speakers accordingly until the proper balance of level is attained. If you would like to change the level between the mains, you can use the [BALANCE CONTROL] either located on the front panel of the receiver or in the Set-Menu. A common challenge people have is that they try to adjust the main speakers to match the center or rear levels. If your center speaker is louder than your mains, You cannot adjust the main level up, you need to adjust the center speaker level down. All speakers need to be adjusted to match the main level.

SOURCE: Speaker output

Yes, there are relay type switches associated with those outputs. Your RX-V1 is not dying.
Just plug a pin plug in and out of the dead channel to bump the switch. You will hear the speaker
come on. If it doesn't come on,do the plug jack in an out of the pre out again. It will come on.
You can use the test tone to check all channels and rebalance volume levels. You are making the
pre out connect to its power amp. It seems the problem got better when activating those switches. Most likely a cleaning issue. You can also jump the mains and center, and there is also
a modification to jump all channels. I bought my RX-V1 very cheap because of this and love it.
Of course outboard power amp would solve all, but getting this reciever to connect to it's own
power amp has been thrilling as far as bang for the buck. I do use the front effects also, and like
them. It may seem like a pain, but it is worth it to get those channels going.

SOURCE: RX-V1 (No left main channel sound)

Sounds like the output stage of the amp is bad. Needs service.

Charlie

SOURCE: left and right speakers has no sound?

Just got my second dsp-a1. Heres the deal, if you have already checked all connections and have the correct source selected, but yet still dont get any sound from the MAINS left and right, heres what to do. Make sure you have proper bypass connectors in the rear where it says main left right. My new receiver came with the 2 bypass pointing up/down. Change them to the horizontal position. Make sense? They should look like two minus signs on the back of the receiver not two II , but rather = . Hope this helps, cause it saved me from what i thought was a blown main channel!!!!!!!!!!!!!!