Hi Matt,
great stuff so far.
I guess that given the set is on its third CRT, it is no surprise that the ECH35 valves don't want to play at VHF anymore.
Yes, your set has cleaned up very well, almost like new.
I once had a 1946 HMV 1804 that was like new (since sold to another BVWS member). On the rare occasions when sets turn up like that, it does make the restoration so much easier. Far fewer problems with noisy pots, valve holders and switches and also there is far less chance of failing transformers. Of course the cabinets are also much better if kept dry.
The set in question had the original Emiscope 3/4 that was also like new and the EHT transformer even worked! I've found some pictures of my actual set from before I restored it here :-
https://www.radiomuseum.org/r/hismasters_1804.html
The labels were fault dockets, stating that the owner was Mr Fox.
Anyway back to your set. Does it have a rubbr mask? If so then that has also survived well. 5:4 ratio 12" masks are hard to find.
Keep up the good work.
Cheers
Andy