Well i recapped this unit a while ago now and i am getting hum, every cap has been replaced including Electrolytics.
If i reverse the plug the hum gets louder so i know i have it plugged in correctly.
I double checked and doubled checked the circuit, all caps are correct values or within range, i cannot understand what causes the hum.
I dont have a tube tester, could it be a bad tube? i have tried moving them when its on but it makes no difference.
When its playing apart from the hum the sound is clear and the amp has good volume.
I even replaced the crossover caps in the speakers too.
Anybody any ideas?
Thanks
David

Sounds like a tube with a heater-to-cathode short. If you had a tube tester it is likely that it would pick this up. Without one, you will have to substitute known good tubes, one at a time, until you find the culprit.

Is the hum affected by the volume control? If so, the problem is in one of the tubes *before* the volume control in the circuit. If not, after.

Also check all your shields and grounds.

-David

I suspected it maybe a tube, it was in poor condition chassis wise, a few caps had thrown wax on to the tubes, im suprised the output transformer was still good.
Thankyou for the answer, i really need to invest in a tube tester.

Update on this it has to be a tube, ive just spent the morning listening to it, one of the modifications i made (reversible if i sold it) was to wire the external rca jack that went to a tapedeck, as an input so i could hook up a cd player.
I just tried it with a cd "Spice Girls Forever" and for an amp and speakers from the 1950s it blows me away with the amount of Bass and Treble, RCA certainly new how to get the best out of a small amp.
I have a place close by that sells radio parts, he also has second user tested tubes, he said i can borrow the tubes to do a swap, obviously if i find a bad one i will buy from him.
His opinion was the same probably a bad tube