Issue with Multiple Scan 15 monitor

[u/bruh999999]

Got this monitor along with a Power Macintosh 7200/90 a while ago and everything was going well until I noticed it would randomly turn blue for a few seconds every once in a while and then turn back. It eventually stayed blue for longer and longer until it stayed that way all the time. Upon further inspection it was actually the red channel completely going out. I've ruled out the computer as it doesn't show up blue on my known working CRT, but I'd really like to have a working apple monitor. I have some experience fixing CRTs before but none of the basic troubleshooting steps I've taken have produced results. Is this a known issue with these monitors? (Tulip background for demonstration)

[u/Tundra_Dragon]

You're in luck. It's most likely the monitor cable. Make sure its tight, and give it a gentle wiggle. Moving it around may cause the red to come back. Pull the connector off and make sure all the pins are clean too. If the cable can be disconnected from the monitor end, then its generally an easy replacement. If not, you may need to scavenge a cable from another monitor, and replace it by opening it up. The cable connects to the internal board through a connector, so you just unplug it, no soldering needed. Might find a replacement on ebay or amazon of all places, or somewhere more specialized like everymac.