Well, I finally decided to finish the gauges. Thanks to eBay, I found a set with under 2k miles that had some damage to the housing. Maybe they got crashed up and replaced with new ones once upon a time? Who knows. I already wrecked one crimp ring trying to close it with a pliers so I decided to make a fixture. Oh sure, go to Home Despot and buy some PVC pipe that's the right diameter for a fixture. Not me. I've got a bunch of tools in my shop that hadn't gotten a lot of use lately so I cut a piece from the scrap street plate I had left over from other projects, cut the sides flat on the mill, drilled bolt holes and mounted it to my lathe's face plate so I could open it up. When that was done, I smoothed the hole with some emery cloth and wrapped a bit of tape for paint protection.
Now just drop in the crimp ring, the glass and the housing.
Then gently and carefully close up the ring with a drift and small hammer. No points for perfection since you can't see this side once it's in place. This is another gauge that needs a new red zone and some cleaning.
And, all finished.
Super-easy job when you don't have to fight the crimp ring. For the record, I cleaned the faces and added the decal for the red zone, and then picked the best parts from a three sets of gauges I had on hand. The set I took off the bike are older and have a blue face, but the red zone looks the same (I've got a few more decals) and on the whole should clean up nicely.