I know, I know I'm bumping an eight year old thread. I recently unearthed the same monitor in my monitor stash. I don't know if it's the same cap kit or not, but after some searching, I found the manual for this monitor Motorola Model XM500-10 Chassis 19VP102.
Maybe/hopefully some of the monitor guru's can chime in with further opinions.
Really bummed that the manual doesn't detail what all the pins are for on the input connector. It's got 10 pins and they all look like they are wired to something or other on the rest of the chassis and frame. What are you possibly using 10 pins for on a black & white raster monitor?