I have a 19" 1976 Zenith Chromacolor 2 set. When I got it, the vertical would be "jumpy" and you could tap the set, and it would be normal. I replaced the 9-92 (Vert module) and it was fine. It started up doing the same thing again. I replaced with my last 9-92 module and all seems well. My question is: Did I just have a short lived rebuilt module, or is something else causing them to fail early? I know "contact points" were a pain in the ass on these, but all seems clean and tight. I won't be too concerned unless this module fails early. Suggestions?

clean the connectors and the size/centering pots with deoxit.