Dani wrote:
Replace the flyback transformer part # Tlfa01365, & resolder the
horizontal drive, & power supply section. Hope this helps.

Thank you so much for your suggestion. I'm still not sure if the flyback
is bad. Lets see if I can get a new one locally. Probably not a
PANASONIC - might be second source junk too. I'm in Paraguay.
If so I'll trash the monitor - not worth it.
The problem is not with the horizontal deflection but the video signal
is partly blanked (masked) out. The unit had no problems with the video signal
when the picture started to wobble horizontally. So I still guess that I
made a more or less dumb mistake when replacing the fried plug. But I
marked the four wires and the fault is the same either way they are
connected - beats me.
Good advice to resolder the horizontal stage and the power supply. I
already had to resolder the complete video board on the neck of the CRT
at an earlier occasion when sporadically colors were missing. The whole
PCB seems to be soldered very badly. One can't even see the difference
between a cold solder joint and a good one. What kind of solder did they
use? Not lead-less I think because the unit is so old.
Man I love the old Tektronics which came with a roll of silver solder
and the warning not to use anything else for repairs.

Kind regards, Eike