Thanks for all the great replies.
So the "slipping" is only with the trip odometer, not the main one. So this new cluster would likely save me from fixing the trip odometer as well. Will definitely try the drill method for "roll forward" rather than micro-gear dissemble... for someone far sighted, it ain't fun.
Funny y'all mention the drill method, as it reminds me of a story. Uh oh.... Yep, I was 17 years old and delivered pizza for a summer job My folks went out of town for a couple of days, and my dad didn't want me to drive the Subaru for delivery. I drove it anyway, because it got better mpg than the pickup. After that I DID figure out the drill rollback method for that car, but burned out his drill in the process. He never knew about the rollback, but wondered by his drill no longer worked!
-Chuck