[Arran]

Yes, that looks like a home brew, but a nicely made example though. The first point of failure is usually the interstage transformers, followed by the solder joints on the tube pins, and every other solder joint. Also the filament rheostats sometimes fail, although you can usually spot that as there will be physical breaks in it, and sometimes the RF coils will have an open winding or become unwound. Overall whoever made this chose good quality parts, I don't see any cheap pot metal bits like some of the factory built sets would have, and they were very fussy about how they laid out the wiring, buss bars with nicely bent joints. Electrically these are very simple but the construction was often very nice to look at.
Regards
Arran