The red colour channel numbers might be the cpu indicating a problem

I concur.

Also, there is a difference between red/used to be green and red/used
to be pale green. The channel numbers may always have had some red in
them, you just never noticed it under the green.

I've fixed a lot of dropped tv's and monitors by resoldering
connections that popped loose. Make sure you check all of the solder
connections, esp. the ones on the tube socket and in places where
boards come together.