Could it be held in place by adhesives? This is probably a long shot, but try searching on youtube for honda tach or speedo repair videos. I've fixed several cell phones using videos I've found there. For 10 bucks you can repair a $500 phone that the store says they can't fix or charges you $100 to do a 10 minute job.
If it is adhesives, softening it with a heat gun or heating pad is probably the best way separate it from the case. Sorry, but this is uncharted territory for me.
I suspect you are correct. After repeated attempts, I have failed miserably.

Will give the U Tube idea a shot. I doubt most folks have tried to do this. No reason to.
In this case, the "new to me" tach is delaminating from the face of the dial. So, I thought I'd use the face off of my old "crushed" tach. The old one looks fine. The "new to me" tach has a plastic film over the numerical face and it's peeling off and already contacting the tach needle. Pretty sure this will result in a not so good situation if I don't deal with it now.
Heat is probably the trick (if that will work) but, we'll see or, I'll seek out another used tach. Thanks for the reply.
