I've had a quick look in the manual, and the resistor you need to check is R235. It should be 10 ohms. Perhaps this would be a suitable replacement:
https://cpc.farnell.com/neohm-te-con...-5w/dp/RE07246
I also looked for the CRT details, but unless I've missed it, the manual doesn't seem to give details about CRT types. Certainly, 370KTB22 is the model number (370mm meaning 14", of course), but I also failed to find anything useful about it online. I'm afraid my examples are up in the attic, so it won't be easy to check the part numbers of those. But as I say, look at how dark the screen looks. The hi-res ones are almost black - lovely