Check your wiring, switching L&R input...does the bad channel switch? After this test, switch back the inputs, and reverse your speaker outputs. Then reverse all cables...so you run change both ends of input and speakers wires...so use your L wires as R, and visa verse.
Also, check to see that your IEC power cord is tightly plugged in. I had a heavy power cord, and the neutral [big pin] was loose, and for some crazy reason, only the right channel would act "funky".
And can you see that all of the filaments of your tubes are glowing, when powered up?
Also, check to see that your IEC power cord is tightly plugged in. I had a heavy power cord, and the neutral [big pin] was loose, and for some crazy reason, only the right channel would act "funky".
And can you see that all of the filaments of your tubes are glowing, when powered up?