OK. When the screen is "reddish", I'll bet there is absolutely no green in the picture, correct? That's because I think the green tube is intermittently cutting out, giving you a "magenta" picture.
This may be a super easy fix, but you need to take the front off of the set to see the CRT drive cards for each tube.
The front speaker grill must pulls off, then there is an access panel that you need to remove.
Once you have that open, carefully reach in and wiggle the green CRT card. The picture may just snap right back to normal.
If that's what happens, the fix is to remove the drive card, blow it out with compressed air, and put it back on.
It's a little tricky to get the drive card off. First make sure the set is unplugged. You'll see a metal clamp that secures the base of the drive card to the neck of the tube. You'll need to loosen the clamp, but you'll see that there are some plastic "fingers" that the clamp tightens against, and the fingers press against some cloth tape around the glass. Over time, some adhesive seeps out and effectively glues the plastic fingers to the tape. All you need to do is use a small flat blade screwdriver to pry away as many of the fingers from the tape as you can reach, then just gently wiggle the board off of the end of the tube. Be careful not to accidentally bend any of the pins that come from the tube, they are very difficult to re-align.
Try that, let me know how it goes, and thanks for using JustAnswer!