This amp arrived on my bench owned by a friend with a few problems, It was bought at a flea market but wasn’t quite perfect. It had been dropped, had a crack in the frame, a bent corner, dead tubes. I did the chassis work and replaced the standard 811A tubes with heavy duty 572B tubes. I re-tuned the input coils on each band for the most drive at the lowest SWR. Then tested the amp into a dummy load on all bands, the fresh tubes made a big difference, the amp was ready to return to my friends ham shack. Bruce McCaskie N6THN