Kortek 2914-f dark spot shadow on screen

[Yoeddy1]

Hi guys,

On the upper right hand corner of my screen, there is a shadow.  The image is written, and otherwise the picture looks great, but this dark spot that overlays the image is annoying.  It's definitely the tube as another chassis produces the same thing.

Any recommendations where to begin troubleshooting?  Do I need to move the yoke around?  Yoke chucks?  Magnetic strips? 

If there are any documents or videos for troubleshooting, that would be great!

Can I touch the yoke with the power on to move it around?  IF so, where is safe to touch?

Thanks,
Jason

[grantspain]

if you put a magnetic screwdriver near the patch does it alter it in a positive way?

[mgb]

Does the dark spot have a purplish or rainbow color to it.
Sounds like it may need to be degaussed.

[Tithis]

As long as you are smart there shouldn't be any issue with you touching the yoke. Obviously you should avoid touching any of the exposed windings of the yoke and unless you specifically need two hands for something like inserting a rubber yoke wedge keep one arm behind your back.

It could be that the yoke simply isn't positioned right, can easily cause dark spots along the sides or purity issues. However certainly start with degaussing the tube. Doing a yoke adjustment is not fun by any means and can take awhile to get the purity and convergence right again.

[mgb]

Before messing with the yoke, make sure its not just blotch that degaussing will fix.
Why not post a pic rather than having people guessing.