Removing underbelly material, what might I be getting into?

You can't hurt anything with that commercial lube but it's actually just a non-ionic surfactant (soap) and water. I would try mineral oil or a vegetable oil.

If you do have to get into the underbelly area, don't sweat it. Remove the screws and cut the sealant with a utility knife. The under belly sheet should fall off, easily. You can seal the material and the mating edge back up with caulk when reinstalling. Put the screws back into the same holes.

Good luck with your sticky valves.