Thanks for your reply. I did see this before, but thought I would check if it was really that hard to disassemble or if maybe someone has run into this when upgrading to LEDs.This may help you get it open.
https://www.jalopyjournal.com/forum...r-how-to-update-your-vintage-sun-tach.297171/
That looks great! I got the LED bulbs yesterday, but don't know how to get the tach apart to get to the bulb. I don't want to damage it. It's been in my car for probably 40 years and I don't remember exactly how it's put together.