rca focus problems

[drh4683]

Well,

I got into the set today, basically all components in the HV area tested within tolerance. I did hook up appropriate test equipment and adjusted cathode current on the h. output and monitored voltage drop on the 6BK4. Basically, everything aligned well, cathode current is at 220ma. Focus voltage about 5KV and the HV is just above 20KV. Picture quality did improve, but still not good enough for my liking. My suspect is the crt. It seems like its going dead on me. I have the screen bias fully advanced to get the green line to show up. I need to "zap" it to try to get some life into it again. I am having a heak of a time getting good red purity. Ive got the adjusting components properly set on the neck of the crt but I cant get the purple and greens to go away on a red raster, even after demagnatizing. I tryed new purity rings that made no difference. A weak crt doesnt cause this does it?