I know there are many posts on this & I've read as many as I can find. I learned a lot from these--but still unable to solve my problem. Just completed Metalbone kit restoration following his very good instructions & includes C97 replacement. Have also replaced C92 & C98. C91 OK. Checked all voltages and as far as I can tell they are where they should be. Playing MP3 player through AUX inputs. Left channel sounds perfect. Right channel distorted pretty badly especially at high volume. Have replaced or swapped 12AX7s in audio path without any change. Have swapped R & L pairs of output tubes without any change. Have thoroughly cleaned tube pins, sockets, switches and controls. Have checked all resistors in audio path (comparing L & R) & all check OK & very close. Don’t have a scope but am using a newly restored T-1 Heathkit signal tracer with a speaker which is a pretty decent trouble shooting tool with some limitations. Sound on L & R channels at volume control is clear. On V-14 C52 and C53 sound clear at outputs. When signal reaches V-13 (12AX7 right channel driver), sound is distorted at C79 & C80 and seems quite over modulated compared to left channel at same points. And of course it is bad at the two right channel output tubes. Would appreciate any ideas on what I may have missed in my attempts to trouble shoot this. Anything obvious--a resistor that checks good--but is bad, a bad tube that appears to be good, a bad solder joint----?? Sure hope it isn't the output transformer. Thanks.