Tim,
Whats the chassis number? I can send you a schematic if its a pre-66 set. You will need it to figure out the disc.
The 87-disc is probably a dual capacitor but not quite an "integrator" and is most likely your trouble. It can be built from 2-3 separate caps/resistors. '
Also, Zeniths of this era had issues with open height/linearity/hold pots.
As for the flyback, replacing paper caps in and around the damper-boost circuits off the fly will cool it down, as it probably got hot before the vertical crapped out. Its all related. Long ago I fixed the arc-trashed flyback in my RCA CTC12 with a brush-on coating by GC,
http://www.alliedelec.com/images/pro...S/70159781.pdf
DAve