I just picked up two CRT's over the last week a Sony KV-34XBR800 and a Toshiba 34HF85; I must say that I like the picture on the Toshiba better, better blacks, better convergence, but there is one thing that is bugging me that I am trying to fix with the Toshiba, basically, I have greenish spots in the corners of the picture tube. Immediately I think its a geomagnetic issue (perhaps there is a service menu adjustment) but perhaps it is a deflection yoke issue.

So I guess my question is, is there anything I can do in the service menu to fix this or should I just start to readjust the deflection yoke?

I would leave the yoke alone, unless it seemed loose to very gentle twisting in the screen plane. Try magnets first (no Nd/Sm rare earth types).

A crosshatch or focus (dot grid) pattern can be used to check the yoke's alignment, at least for the sake of convergence. Send magenta first (no green), ideally at 1080i over HDMI, at low contrast.

Wouldn't know what to recommend for purity checking, other than flat fields of red, green, blue, and gray.

Where can I find these magnets and are there any instructions or simple rules for applying; as in, "if you have green spots in the corner, put X size and length magnet here". I LOVE this tube, it has the picture that I have been waiting for, basically a 34" shadow mask based CRT that isn't huge and oversized.