Mine is a series 2000-0 with a max of .50 but a 2000-00 has max .25. Either works. I read by using tubing from the gauge to a piece of copper tubing that fits inside of the screw hole. I can take a picture later if necessary.
Thanks for all the helpful info. If you can take a picture, that would be great. One thing I have noticed, is that the glass hasn't turned black. Just the usual white on the upper right side
![[Hearth.com] m-55c-fs "ISSUES" [Hearth.com] m-55c-fs "ISSUES"](https://www.hearth.com/talk/data/attachments/129/129710-33766d2e3725883a3bfe707b80646a8a.jpg?hash=ShqnP4JgRX)
![[Hearth.com] m-55c-fs "ISSUES" [Hearth.com] m-55c-fs "ISSUES"](https://www.hearth.com/talk/data/attachments/129/129737-e7ab3eb8adc6439ea88d5c03b16202ba.jpg?hash=F8WiAUokzO)