Part # 6211439
Instrument Glass Repair Kit

At less than a sixth of the price of a new housing, this is the way to go if your problem is limited to a cracked lens (or two). That's the good news. The bad news is that the instructions are written in the typical German fashion, meaning that the writers presumed a level of familiarity and competence that may or may not be there. Fortunately, there are places on the internet where you can find the correct procedure to disassemble the instrument housing, but when it comes time to remove the old lens, that's when things get interesting. The lens is basically glued to the housing, so the only way to remove it (once you've removed the visor ring) is to break the adhesive bond with either a knife or a screwdriver, then slowly go around the rim until the lens is free. This is what they mean by "prying" it out. Now, if the lens is cracked, this method will cause the crack to propagate and the lens will break, but that's no big deal. Once the old lens is removed, you should take a moment to note how the inside of the visor ring is shaped. It has a groove about 2 mm from the bottom that needs to match with a land on the instrument housing. This 'land' is actually the lens edge sticking out from it's base on the housing itself. Now that you understand how the visor is attached, clean up the remaining adhesive from the instrument housing. Best to use a sanding block big enough to cover the entire circumference, otherwise you may end up with peaks and valleys when you want a perfectly flat surface that is also perfectly parallel to the instrument housing. The rim where the lens will rest (I'll call it adhesion rim) is raised and should be exactly 2 mm higher than the wider circle around it. If it's too tall, the visor will end up sticking too far up, resulting in a slight gap (which no one will be able to see). If it's too short, you may never be able to fit the visor correctly. So, err on the side of too tall! Second tip: the lens MUST be perfectly centered on the adhesion rim, or the visor will end up lopsided. Instead of using the super glue provided, which can only be dispensed from the spout, I used a Gorilla product that is also suitable for rubber and plastics, but has a brush applicator as well as a spout. The instructions would have you lay the instrument housing flat (and presumably upside-down), and apply adhesive from the inside while the lens is already in place. From experience, this is a recipe for runs and fogging of the lens, so I opted to hold the housing right side up, applied the adhesive to the adhesion rim, then VERY CAREFULLY lay the lens on top of it so it's perfectly centered. When I re-installed the visor ring, I ended up with a minor gap, mostly on the bottom of the circle, where no one will be able to notice it. The measurements I took before stopping the sanding process indicated between 2.2 and 2.4 mm, which I considered 'close enough' to 2 mm to go on, especially since the measurements were too tall and not too short. The whole process took less than an hour, which included the repair of one of the threaded inserts. Bottom line, worked as intended, but don't rely too heavily on the instructions. The written part is a bit oversimplified and the pictures not very helpful.