Blues Jr. Tweed Hum & Distorted

[Perkinsman]

Hi guys, this amp had a blown F1, which I replaced and watched V4 shorting before my eyes. I replaced V4 & V5 and the fuse held but there's still a hum that volume has no control over. When I plug the guitar in to play, its garbled and distorted and the volume climbs and drops. I touched up both power tube solders & cleaned the 2 grounding wires to the chassis but no change. I temporarily tacked in a 47uf & 3 22uf's but still have the hum. I switched V1 & V2 but no change. As I was taking voltages I found that the hum goes away when I touched several of the resistors with the probe but returned as soon as I withdrew it. Can someone steer me in the right direction please.

[xtian]

When power tubes fail (as yours has) they often take out their screen and grid resistors. Check those out: R33,34 and R35,36.

[Perkinsman]

Good call, it was R35. A lesson learned on a shorted tube. Thank you!