I did not find that there is a seperate section for tips,
so I hope it is okay to post here, even if it is a minor tip such as mine.

I'm sure all of us have had a 3/4 tube of silicone sealant harden up on us at one time or the other.

Slice that plastic tube open to retrieve the now congealed silicone cylinder.

It will serve the same for you in cleaning a sander belt, as the more expensive crepe blocks will.

Bob