Help wanted resurrecting 1969 Zenith 12A10C15

[Electronic M]

Rubbing alcohol or Goof Off is best for cleaning HV cages. There are thin wires exiting the side of the flyback be careful not to disturb them too much.

One thing I often to do is remove the HV rect insulator cup and clean the bleep out of it...You clean it by discharging the HV (lots of searchable info here on that), removing the HV rect tube, unscrewing it's socket from the insulator and unscrewing the insulator from the chassis. Clean that insulator spotless, and if there are any black spots that look like they go through they will need special treatment like on the previously mentioned similar Zenith I serviced.

Once you've cleaned or perhaps before you clean it is wise to run the set briefly to find the exact spot it is arcing, and or better localize it so you can fix that easier/better.

Here is the schematic. Pics are a bit blury so if you need to see an area I can take a closeup. There is NO focus divider off the HV in this set. It looks to be a low voltage focus tube the highest focus potential is the 720V boost line (which is low compared to 3-4KV focus tubes found in consoles of the time).
click on pics, then click flickr's full size button to get bigger versions.
DSCN2718 by Tom Carlson, on Flickr