Veg,
Just looking at your trouble- thought I would run something else by you check out. Do the VERT HT and VERT LIN controls both have a reaction when you turn them? Also, does the effect on the screen when these controls are turned look smooth or maybe a little abrupt? There is usually a fairly high voltage on these controls in a tube set. If you heard a sizzling sound inside them one of them may have arced over inside and have a bad spot. You might check any resistors connected to these controls too. If one of those controls was arcing it could have caused a resistor to change value or open up. Good luck.
Jeff (PUNK ROCK DUDE)