RPM Guage has heat? bubbles...

Check out the bubbles on the RPM guage... I bought it in AZ so i'm guessing it's from the heat.

Can the RPM guage be replaced without losing the mileage?

 

Welcome

 

Wow, 93K, nice!

Replacement of the instrument cluster is all-or nothing, so to get a new tachometer, you'll need a new cluster. You might try removing your cluster and carefully removing the plastic face (look up how to do this, you may need to soften adhesive or something) so you can use a pin to pop the blisters. Hopefully that would allow them to deflate, but I have no idea if there's adhesive in there or if it would re-adhere after all these years.

 

You could get a new cluster and then try this: https://www.instrumentclusterstore.com/mileage_correction.htm

 

Also, if you are good at soldering, you CAN swap the eeproms. Lots of posts and vids out there where people have done it.