Which chassis ??
On all chassii if they have plug in transistors solder them in.
Also check the 330 ohm resistor on horz module, 9-57 or 9-90
Be sure all the safety caps are the new orange ones.
Check the 1.5 ( IIRC ) ohm resistor at base of hoz out transistor.
For brite issue on uprights check the 9-88 & 9-89 for PC cons
under the white resistor packs IF it uses them.
On flat chassis the ends of the terminal strips often make grounds,
be sure they are not breaking free.
Chromatic switches get noisy also.
That will keep you busy !
73 Zeno
LFOD !