[Amps] TL922-one tube dead?

[Andy Diethard Hansen]

Hi Group,

My modified TL-922 (230V/50Hz) created some humming noise in the past month
(may be filament transformer-somehow remaining after PA switched off) before
going to half power after 15 years, yesterday. Some smell came from the amp.
The noise now is very strong  when switched on and will reduce a little
after a while.
Looked from the outside first like some arcing on the board right next to
the left upper corner. One tube is now not heating anymore (left from
front). Grid Idle/plate current and power out are down to 50% normal in CW
and SSB. HV is normal. I assume one tube has gone to heaven (matched
pair?-3-500Z orig.)

Questions:

Where do I get quickly a reasonably priced (set?) of tubes and a
FILAMENT Transformer???

Any other advice/comments/experience? tnx for help

Andy HB9CVQ
www.qrz.com/hb9cvq