Now that I have the Sams, I see this set uses a 0.45 amp filament string. It should have a 8.4 VAC @ 0.45A 10ADP4 CRT , but instead I have a 6.3VAC @ 0.6A 10ABP4
I ran into a similar issue with a Zenith bugeye set. The CRT worked OK, but certainly wasn't as bright as it could be.