DuMont RA-105 picture distortion
 

First post so be gentle. I just brought this beast back to life. Replaced all electrolytic and paper caps, DeOxIt on controls, replaced rotted zip-cord blew a ton of dust out of it.

I'm getting a good clear picture but the top inch or so has a horizontal bend to it. I've been through the typical setup (avoided touching the IF strip) to no avail. It doesn't seem to be affected by the brightness or contrast controls so I don't think the power supply is at fault.

Any ideas? Sync separator maybe?

Also, this set has a monster chassis with separate HV box. Really tough to operate out of the cabinet. I have the Photofact which cautions about pulling the horizontal oscillator to kill the HV. It suggests taping off the HV lead to avoid contact.

This suggests that the chassis can be operated disconnected from the picture tube for servicing and alignment. Is it safe to operate with the yoke unplugged? I really don't want to damage anything but pulling the chassis for every minor tweak is a real ordeal.

Are you using a VCR as a signal source? VCR's have a bad habbit of 'flagging', which is a bend in the top 1/8th or so of the viewing area. I don't know if anyone has figured out a cure for VCR 'flagging' yet. I would bet that someone has.....

No, the source is analog cable which locally is still NTSC on channels 2 through 13 as well as mid-band channels that the Mallory Inductuner picks up just fine.

If you adjust the horizontal hold control "just slightly" in either direction without it losing sync, is it still there?