How do I remove the rubber from these rollover guides?

Long version with my 'thoughts'...

Some of them just have the upper ring and it is easy to remove. Some just have the lower ring and I thought "it's not in the bad if shape, I'll just clean it up". Some have both and the only way I can think to remove it is by using a dremel cut off tool. I would really like to remove them without breaking anything and clean the plastics in an ultrasonic cleaner, but then I am wondering now how difficult it would be to get the replacements on.

Thanks for the help!

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This was an amazing time and effort saving solution!

I put about 6oz water in a plastic cup, microwaved for a minute, dropped the piece in the cup and left it in there for a minute, removed it from the cup and twisted the rubber piece right off. It almost seems like the old rubber had bonded to the plastic, as it was real smooth on the inside and was stuck.

I could have spent hours trying to get these removed and risked damaging the plastics, and I got them all removed in a few minutes.

Thanks again!