I've been able to improve the focus on my Sony CPD-G520 by carefully
adjusting the pots on (what I think is) the flyback. I can get the picture
quite nice and sharp, but it always seems to be off a little bit the next
day. I'm wondering if I need to put something on the heads of those two
adjustments to lock them in place once I find the best setting... or if
there's another problem that's causing the focus to be inconsistent.

Any thoughts?