Marshall Valvestate 265 with one channel hum

[Judson]

I have a Marshall 265 that has a hum on one channel. All of the volumes and controls are turned down, I have replaced the rectifier and filter caps, repsoldered the broken solder joints on the board and I can't find the problem.There is a 4 volt saw wave on one channel and now that i resoldered some broken joints I also have a high pitched squeel riding on top of the saw wave. I have pulled the tube, no help and also one of the ten watt resistors for the tube R-18 gets a little too hot.

I would be grateful for any help you can provide.

Thanks,

Judson