What happens when you read your PAL with your programmer?
Do you get an empty equation? If yes, it might be faulty, then again it might be protected - I don't have one to check.
Is the equation inconsistent between reads?

Looking at the schematics, yes the PAL looks like it's used as an address decoder. PinMAME doesn't use the PAL equation. It just has a high level implementation.

Does the date code stamp on your PAL line up with the era of your game?

It's possible to read some protected PALs which are just combinatorial logic, registered logic is another matter.
For example, see here:
http://www.vcfed.org/forum/entry.php?315-Cloning-a-PAL-HAL-%28Part-2%29

16L8 PALs are combinatorial, so in effect they are like a very fast ROM.

If someone wired one up to interface as say a 2716 EPROM and read it in an EPROM programmer, it should be possible to create an equation from the output.

You just need someone that's willing to go through the effort.

Yes from memory we managed to reconstruct the PAL equation. Let me find my compiled copy and I'll send it to you. You can program a PALCE16V8 chip as a replacement.