Most old Zeniths FBT's I changed were turning brown at the doughnut.
These were always bad from shorted windings.
The fiber board is mostly for focus & H centering parts. If it has a
stick rectifier they went bad & often took resistors along for the ride.
Arcing can be stopped by cleaning up the area & being sure everything
is A OK. ( an NOS FBT from Zenith has everything used & also the HV rec socket & wiring ).
Your biggest hurtle is finding a hoz out cheap. Most go to hams & the
prices are high
73 Zeno
LFOD !