Sorted it! I managed to get the wrong fusible resistor to replace the blown one, I got 0.25w instead of 0.5w. I only noticed last night after looking through the schematics for ages trying to figure out what else could be wrong.
I replaced the blown one with a 0.5w FR2R2 as it should be and we're working again.
The issue was basically there was no power getting the the vertical deflection circuitry which is powered from the 24v line. That particular resistor was the fuse for the 24v line coming from the FBT.
It looks like a case of PCB component gunk becoming conductive over time and causing a short and blowing the fuse, as the blown fuse was well gunked from a nearby cap which covered a diode as well.
Another monitor saved from the tip!