I just changed the valves/tubes in the AFD.
It took minutes and was so easy. 4 screws on the back cover, instant access to valves. Remove spring retainers. Pull the 6550's out, line up the El34 and push home. Put the spring retainers on and put the four screws back on.
Switch on - Auto-Bias while it warms up. Job Done.
How cool is that! Easiest tube change EVER!
I didn't like the EL34's in this amp. It kept the cool treble and afd sound but became very bassy and lacked mids.
That's cool though, it'll only take a few moments to change them back