The entire right channel is out on my GF-666Z. It was working before I sprayed DeOxit into the sliders. What has blown??

It could be that the slider itself has failed. Do you get anything at all (any kind of signal or voltage) from the speaker output side? (Try themain and external connections.)

After spraying some contact cleaner in one of my RC838 sliders (the bass controls), it stop working. The spray affected some kinds of plastic and damaged the plastic piece which holded the contacts against the slider rail resulting in an open slider.

I was really lucky to find the same original part from ALPS the next day. It was the LAST !!!!.

If the slider has 3 points (mono) you should read 0 at one pair of contacts (use an ohmeter)
when the slider is at MAX or MIN position.
If the slider has six points (stereo), you should do the same, but you will need to indentify which group of contacts are related to the bad channel.
Of course it you touch the slider pads with your fingers, hum in both channels would be heard (put the sliders in the middle before trying this), so the issue can't be from the power amp.

Thanks guys! The LED meters seem to indicate that the amp is sending out L and R signals, but by the time the signal reaches output, it's gone. I also tried the headphones - still only left channel. If I turn up the right channel all the way, I can hear it a little.

I'll open it back up and see what I can find out with the meter.