I'm not sure which Predicta you have, nor have I had a chance to work on one yet, but they should be mostly alike, found this, so.
http://www.earlytelevision.org/pdf/p...sams_439-1.pdf
Obviously the missing voltages are the first task.
No 140v = no IF, thus no video/ sound.
No 260v C will kill the horizontal oscillator/ HV, and thus you have no boost and it will be at low of 200v ish.
Looking at THIS schematic anyway, there has to be something really weird wrong for 260v C to be missing, without that, the cathode of the audio output will be all wrong, and thus 140v will be wrong as well.