Loss of volume in right channel

I've noticed that my system is intermittently losing volume in the right channel. Usually starts out fine when the system is first turned on. Plays well for a while. And then the right channel will suddenly cut partially out (never a complete loss of volume). Then it will come back again. Also, I occasionally hear a sizzling noise in that channel.

I checked my source equipment, and the problem remains consistent with the right channel, so I'm pretty sure it's not my CD player (most often used source). Speakers are in good shape. Swapped pre-amp/amp cables, and problem remains the same, so it's not a cable problem. I'm thinking the problem is in the pre-amp, which has had a couple of "open" circuit problems in the past. Any thoughts ? Thanks.
Sounds like a problem I encountered a while back. At first, I thought it was the cdp, then perhaps the preamp.

So I started to zero in on the problem using the process of elimination.

1. Switch the left and right ic connectors at the source (cdp or tt) only. Did the problem switch channels?

2. If it switched, then continue on by along with step 1, now also switch the L & R ic connectors at the amp only. Did the problem switch channels again?

I don't have my notes handy to be accurate with the deductions, but performing the above steps as well as substituting another set of ic's into the mix, would help eliminate one or more components and/or ics.

In my case, it turned out to be the right channel interconnect used between my cdp and preamp that had a questionable connection.

Crazy, I'm going through the same exact thing right now (but in the L channel).

After about 5-10 minutes the left channel cuts out and begins to vary in volume. This is sometimes accompanied by static coming from the speaker.

Stehno's method is almost exactly what I did which helped me determine that my amp was faulty. When I switched the ICs on the amp end only, the problem remained in the left channel. When I switched the speaker cables on the amp end only, the problem switched to the other speaker. This told me that the speakers were ok, the source componentes were ok, and the amp wasn't. At any rate, the amp is now on its way back to the manufacturer.

BTW, what amp are you using?

Most-likely it's an amp.

First off we need to know what amp you have (tube? transistor?)

If you have a tube amp you'll definitely know it's a tube(s)

If you have SS amp and can reach an output transistors, you should check-compare its temperature on different channels.

Replacing transistors in SS amp is a-bit more tougher and may require tuning and matching. Often you would want to replace output transistors on both channels especially if you can't find right replacement.

If you connect only faulty channel, you may hear clipping even on low volume while the one non-faulty will play OK.
Pre-amp is a 13-year-old PSE Studio SL. Amps are monoblock PSE Mk Vs. All solid-state.
I had a similar experience with a channel going out occasionally. It would actually come back on when I would walk near the amp and back off when I walked away. I swapped cables and still happened. Finally bought new cables and problem went away.