Fixing the socket terminal was a good idea. I got a wire through the side of the socket, wrapped it around the little holed piece on the inside and the old stub on the outside, and soldered. Left a pigtail until I'm done messing around in that area. It won't survive caveman yanking, but the original terminal wasn't that sturdy, either
With a .1 uf cap in place, I measured 118ma cathode current with the Triplett meter. That's the middle of the 100ma-140ma range given in the schematic. I'm going to quit stressing over this, since the voltages on the HOT and general performance are also normal.
The vertical (drive?) line definitely becomes more visible if you turn the fine tuner CW to the point where focus becomes too sharp and you start to see ghosting contrast lines on the sides of objects. If you back off on the finer tuner, it basically goes away. I'm crossing that off the problem list, too.
Re the linearity, I previously replaced three resistors on the sweep board (R65, R69, R70) and that improved it somewhat. I just replaced three more (R66, R67, R68) and it's about the same. Please don't tell me it's the vertical integrator K1; I have built replacement integrators before, but they're kind of a pain.
Thanks,
Phil Nelson