A couple common problems, open audio interstage transformer?
Wrong bias on 45 tubes. This can be caused by the divider resistors across the speaker field changing value.
Measure plate voltage on tubes to be sure they are positive.
Norm
:hi. i have an atwater kent 55-c early model. i recapped it. installed ceramic sockets. the stock ones were toast. problem is very low volume. any hints to whats wrong. thank you. p.s. the tubes work fine in my other 55-c just fine.