8bp4 tube test on 7vt5a2 motorola.

[fumplet]

I bought a motorola 9t1 and decided to test the tube on my 7vt5a2 set. Picture was super dim with lights off and brightness all the way up. I have a feeling I did something wrong.
I slid both tvs real close to each other and disconnected the 7vt5a2 tube socket and connected it to the 8bp4 still mounted in the 9t1 wood case. did it need the grounding strap to function correctly or was that just for noise shielding?