Predicta Holiday No Picture or Sound

[greggburnett]

I am currently restoring a Predicta Holiday, and am having trouble resolving an issue with "no picture, no sound". I have a faint raster, and an audio hum (hum decreases at full CW on the volume control).
I have reviewed a similar thread on Videokarma, but that has not helped (yet).
Here is what I have done so far:
- Tested all tubes
- Re-capped all electrolytics
- Re-capped the chassis
- Replaced the rectifier diodes and caps
- Replaced R77 with individual resistors (13 ohm, 18 ohm, 8 ohm)
- Replaced R76 with two SL12's
- Replaced R78 "fusistor" with a 5.6 ohm 10W resistor and a 1A fuse
- Re-capped the main board, replaced all networks and the 12CA5 (someone has replaced the socket)
- Corrected a cold solder joint in the tuner filament connector pin
- Removed a solder bridge from the 2nd IF (shorting C14 and R15) , replaced some resistors, and replaced the 5AM8
- Verified resistance values in the fly-back and L23 (okay)
- Replaced resistors R66, R67, R70, and R71 in the Width/Boost circuit
- Checked R5 (Width) and R68; measure okay

Using Sam's as a reference, here are my voltages:
- Cathode of M1: 275V vs. 290V
- 280V Source: 262V
- 260V A Source: 257V
- 260V B Tuner B+: 239V
- 260V C Source: 238V
- 140V Source: 144V
- 435V Boost: 391V at pin 1 of the CRT ( R5 full CCW; 350V centered); voltage seems to decay slowly

I would certainly appreciate some insight...