There is a k7000 medium res series. They're not overly common, but they're out there. Is there a number beginnign with "WG" anywhere around? That would be a serial number or model number. Wells Gardner is unfortunately terrible with their numbering stuff...

That's a k7500, which is medium res (25kHz). If it doesn't look like that, then it's probably standard res (15kHz).
The CGM-2500 is a part number apparently used by a company called QNIC that I've never heard of. I've certainly never seen one of these monitors in any Midway cabinet (or at all, for that matter). It's probably either a replacement, or the cabinet's a conversion to begin with. This appears to be a standard res (15kHz) monitor.
Neither of these monitors would be switchable, which means that you can also check the DIP switches on the boards to identify what the monitor can do based on what the game is set up to output. For the "Seattle" hardware, which is probably what you have for both (and definitely have for the original Blitz), I'd need to know what the DIP switch settings on bank U8 are.
Switches 2 and 3 control the game's output resolution:
2 ON, 3 OFF - Standard Res (15kHz)
2 OFF, 3 ON - Medium Res (25kHz)