Am having a couple of problems with my Marshall 8080:

1: Sometimes no sound will come from the "Normal Channel", if I twiddle the GAIN control it sometimes comes back but sound fades in and out and crackles.

2: I cannot get any reverb from the amp and havent been able to for about 10 years!

I am new to amp repair so please take it easy on the jargon!

I have removed the control board but have no idea what im looking at with regards to the components

Any help would be muched appreciated.