Good idea, but it checks out OK. I perused the troubleshooting section in the Riders service info and found mention of picture blooming. They suggest it could by the picture tube or the 470K resistor in series with the HV lead.
Well, I'm using a 5AXP4 test CRT that I know is good so time to check that resistor. I found it mounted right on the 1X2 rectifier socket.
Briefly it measured around 500K then my DMM went to infinity and stayed there. I then tried a VTVM and got 30M !
I replaced it and viola! Plenty of brightness and no blooming
I recall reading that these resistors can go funky, but never experienced it before.
Just one problem left. While pulling the 10BP4 to install the 5AXP4, the base got hung up in the yoke and ripped out
Doesn't look too bad though. I'll try threading the leads back through and gluing the base on. I've done it before
