Crate BT100 combo amp, humming noise

[MAxDz589]

Hi All,

I’m posting this hoping to get some advice on repair and if it’s even repairable. Reddit post ()

Any ideas of what’s causing this? It happens regardless of the bass being plugged in, and if I smack the top of the amp it works fine.

 

[Old Garage-Bander]

Hitting it to make it work fine again is a big clue that it is repairable.
The trick is to get it to work fine without hitting it.
That's where an experienced technician can open up his bag of -finding an intermittent- tricks.