Okay, my favorite XL 100 has developed a problem.
What is the cure.
My tech manuals don't seem to cover this.
I have attached a few pictures.
The camera makes the colors horrible, but they are not. They are absolutely stunning.
Only the blue convergene problem. Seems to be more prominant on the left and lower portions of the screen.

Looks like the convergence assembly got jarred/disturbed.

or the blue lateral magnet could have come loose. The bands always rotted on older RCA color sets, so not sure that was still an issue in 75, but you may want to check that.

Or could be a blown convergence rectifier diode or a bad potentiometer for the master blue tilt or bow I think it's called. I have a 66 zenith with a blown coil for the blue master left side and causes this exact symptom

nice set!i have the same model and it is my daily watcher.pretty simple repair.just do a convergence set up and you might find the blue coil on the assembly is melted or the pot is crunchy.the etf has a in box xl100 for sale.these are great sets.back in the shop days,we all raved about sylvania s.here in columbus that was the biggest seller.i had forgotten how good these were.love mine and though it was still in the box and crated-i had to do a complete set up and deoxit all controls.convergence was lousy and all switches and controls were inoperable.30+ years of sitting doesnt help them.i may some parts for that set.some controls for the convergence i know i have.good luck and if you need something,let me know.

Well I did a quick and dirty adjustment and the picture is near perfect now. A near imperceptable blue misadjustment at the lower right corner of the screen is all that remains. I believe a little more adjustment of the blue lateral magnet should cure the remaining convergence problem. But I must bring the console to "work bench" height first. It is for me just too difficult to get down on my knees and peer around the set looking into a mirror.