I can't get v.lock (it rolls . . . faster on power up [cold] ,slows
down but still annoying on warm up.

I don't have Supercold handy to isolate the suspect part -

I'm just wondering where to start looking - I emailed Hitachi for
service docs in the meantime.

HS

Use an ESR meter to check all the caps starting in the video amp input
area, through the sync separator and on to the vert def scan gen
circit. Also check the ones in the veret deflection area. You can also
use a scope set to TV-field sync or low-pass synca, and trace out the
mentioned areas to see where the loss of vert sync is lost.

This type of work requires good experience and the proper tools. It
would probably be best for you to give the set out for this type of
fault.

Jerry G.