Must be a kit sets. looks US built but I do not recognize the
chassis or part numbers ( on PCB). So must be based on one of the
very small builders.
Often we saw tires melted away but the FBT works. Most bad FBT's
had shorted turns. Best start is be sure the H out tube has a HIGH
negative voltage on G-1 & cathode current within spec. Take it from there.
BTW RCA, GE & Sylvania used to publish "tube manuals".
https://www.ebay.com/itm/32572606269...Bk9SR9LN-azcYg
They are quite helpful and cover a LOT of things.
73 Zeno
LFOD !