In the interest of thoroughness, I disconnected C3C (the 100uf vert lin pot cap) and C3A (10uf, connected to height control) and checked 'em. Both are good, correct values, not wired backwards.
I left C3C disconnected and wired a fixed resistor and new 100uf electrolytic in place of the old vert lin pot/cap combination. Here's the best height I can get:
Changing the resistor's value affects the height somewhat, with smaller values giving more height. Never more than seen in the photo, however.
The Height potentiometer (R7B) tests in the range of about a few K min to 2.7 megohms maximum (3 meg is specified). I tried bridging some resistors in parallel with it, just out of curiosity. I can get the height to decrease by lowering the resistance, but not increase. That pot would be an ordeal to remove for replacement or further testing. It's part of a two-pot control soldered directly to the board with eight lugs.
Phil Nelson