1971 Sylvania TV - Need Help with Horizontal Hold

[rodmonster]

OK...
So I had the repair guy come back. He popped the back and worked on several things (checked tubes, resoldered endpoints to the power tube for the AGC area, cleaned off some areas hat looked dirty from time, etc). He was there for 2 hours messing with things. It stabilized once or twice then back to scrolling. In the end he gave up and said if I could find a new Horizontal Oscillator Tube - that might fix it.
After he left I turned it back on to see what I could do. It made a popping noise for a few seconds... the picture jumped back and forth and then it came in... clearer than ever.. I was like - huh... what the heck... turned it off and back on.. still there.. I figured well this is nuts but I am ordering the new tube anyway.
Over the next two days I watched the TV for up to an hour at a time as I was working on things in my toy room. Figured if it stopped working - then so be it - I would have a new tube soon to fix the horizontal issue. Well it worked just fine.
I got the new tube last night... (and it was new - old stock - in box - never been opened and it was OEM from Sylvania). Once in - it took a few minutes to come up.... and then the scrolling started... I started adjusting the Horizontal hold, AGC, height, etc.. and it kept going... Worked on it for nearly 2 hours and thought... this is nuts... its a new tube... ok.. well.. I am going to throw the old one in for kicks and giggles...
As soon as I put the old one back in - it stabilized again - without ANY additional tuning.... And I watched it all night as I was in the room - without any issues...
Will it last? I don't know.... Did he do something that inadvertently made it work now.... I don't know...
In the end - it is working and I am pleased as punch!
See pic below...
On a side note... I found a 1977 Du-All Sears 8mm projector over the weekend... took it apart , replaced the belt, reattached old gears, lubed it up, and got it up an d running! =)
Thanks for all the help Yall!!