You need to find what value it is - however, they may not be a schematic available - it's been common practice for a good few years now for repairs to be PCB replacements only, and no schematics (even for dealers).
Assuming it's a little blue disc capacitor? (they are usually, but not always, blue), such capacitor have been a VERY common failure for decades - if you check what it's circuit reference is (C123 or whatever) you may be able to find some mention by googling that with the model number (it's highly likely it's a very common failure). I used to keep a drawer full of all the different values I could source for those capacitors, as they were such a common fault going back long in the CRT days.