sounds like he needs to have his 7500 rebuilt. If your not familiar with monitor repair the 7500 is not one I would cut my teeth on. Contact one of the several people here that do these repairs full time and have it fixed for you.
Security101, ArcadeBuffett are 2 I know work on these. Chad at arcadecup may also.
As a note, this monitor is not a "standard" K7000 series. It is in the K7400 7500 series only, and parts from the 7000 are not the same as the 7500.
And as the 7500 is EGA only if you do not have the TPG or some way of getting the proper signal to it you will not know if it is working 100% (Unless you risk your board in the game)