Removing underbelly material, what might I be getting into?

Definitely try the lube first. Likely they say drain the tank well and rinse, then add the lube to a small amount of fresh water and work the cables.

Run the cables as much as you can, and collect in a bucket, then put it down the drains and run it a few more times. A few times through will likely fix your problems right up.

There was a thing on here a few days ago.. I think someone tried olive oil or something like that and reported remarkable success.
here you go