I picked up one of the GA-5 reissues some years ago, but it has a hum and I put it aside. With the "stay in", I decided to pull it out and see why I put it away. The hum is still there even without tubes. I turn it on and after about 10-15seconds the hum swells from silence and just stays. The volume pot only quiets it "slightly" and it seems mechanical as I feel it hit the stop at each end with some slight movement, there's a small click and either slightly lower hum or back to the same. It's a flat hum, no oscillation.
Took out the JJ's and put in Mullards. No change. Put in Groovetubes (don't judge)... no change. No change with guitar cable (with or without guitar connected).
Included the guts as they are. Any thoughts?
