Issue with EL34 amplifier

I bought this cheap as it had a crackle but I think the issue is actually that the rear two power valves are not working. The heaters glow but there is no voltage difference across the bias points and I can actually keep my finger on the top for a few seconds unlike the front ones. I've swapped out all the valves with ones that were working fine in my last amp.

Appreciate it's not a trivial question but is there a likely candidate for the fault?

Unfortunately I can't access the amp for a bit but if there are some things I can check for (while it's powered off) I could get a list for next time.https://uploads.tapatalk-cdn.com/202...3ebfb25704.jpghttps://uploads.tapatalk-cdn.com/202...7a56df69e1.jpg

The obvious first stab is although you know the tubes were good in your last amp, does the same thing happen if you swap the fronts with the rears?

Expected answer is yes, TBH. But worth a try.

Do all the receptacles for the pins on the sockets look good?