mmm… old amps displaying those symptoms usually need some love on non expensive parts: replacing pots, jacks, old caps and any old noisy carbon resistors… the cost of these is low, but then it depends on labour.
Another easy fix for Eden Travellers: cleaning thoroughly contact points on all the input and effects jacks thoroughly, this is a well known source of hiss and noise in these amps, use De-Oxi or similar product that doesn’t leave dielectric residue. (electronics cleaning). Old toothbrush, dental picks and q-tips come in very handy for this.
Have you ever replaced the tube? Have a picture? Could be that also, a noisy tube… 12AX7? I love TungSols for that…
Right now it has cost me more than I could sell it for, and it still isn’t sellable… which was not what I was hoping for.
It’s an appreciated amp, not uncommon to spot it in studios., give it some loving and if it fixes that… you’ll be rewarded twice, fixed amp, and having been fixed by yourself!