It does look like a shorted green gun in the picture tube, but just to eliminate the rest of the monitor, desolder and remove the green drive transistor from the neckboard and fire it back up. You should get no green video, but if the tube is shorted, you'll still have that green haze all over the picture. If the haze goes away along with the green parts of the image, then replace that drive transistor.
I wouldn't buy a rejuvinator just to attempt to salvage one tube. There is no guarantee that the rejuvinator will even be able to fix it, some tubes are shorted beyond resurrection. Once you are sure it's the tube, see if there is a local or semi-local KLOV-er with a rejuvinator. Or, take it to a TV repair shop (especially an older TV shop), they should definitely have one.
If it is the tube, another solution is to find a junk 19" TV and swipe the picture tube from that.
-Ian