Mind boggled...
To me it seems that adding that gimmick just gives a faster way to wear out the green/blue guns, having a master CRT bias pot on the back tied to the cathodes of the Y-AMPS, and another on the front, on the CRT green/blue G1 that the user can set?
This is prob why it was replaced with a new one in 1973.
No telling what condition it's in now, won't know till I pick it up on Saturday.
