Here is a screen shot of my favorite movie watching set - an '07 RCA 27" TruFlat. I know it is just a Thompson/RCA but it does produce a great picture and has excellent sound, plus it has ntsc/atsc/qam tuners.

The beast gets very little use. It did receive a hefty jar last week when it slid off of a POS particle board stand when the stand pancaked flat.

As you can see it has a dark spot mid center on the left edge of the CRT. It is almost imperceptable, just slightly dark during any normal picture - BUT when a flesh tone crosses that area it is chartruese green.

Any ideas? Damaged mask? Need degaussing?

Doesn't look severe enough to be a bad mask.

Is there a speaker mounted on the side in that location?

It could have a slightly damaged shadowmask; but, it looks like either it needs degaussing or the yoke slipped slightly out of postiion. Many RCA's had a bonded yoke CRT; but, I can't remember if this is one of them.