Hi Bertus
The beam finder displays a 4 to 5 units high and 1 unit wide
The good new is, I think I have located the problem. The focus voltage is too high. When I put the high voltage scope probe on the focus pin of the CRT, there is a voltage drop and I can almost focus the trace. There is a problem with the 6.2 meg resistor and one of the 510K resistors is out of tolerance. I have ordered parts. Finding and using the HV scope probe really helped.
I spent hours trying to find some specs on the CRT, including talking to Tektronix,. If I had known what the range of voltage to focus the scope tube, i would have been able to solve it right away. (Tektronix was no help). I think the tube is probably made for them and that is why no data is available.
Thanks for coming along for the ride.
I will post again if it really fixes it.
Many Thanks, Creede