Remove all broken glass and as much of the silicone glue as possible. A small screw driver works well.
Camber vials (2 outside ones):
If only one vial is broken place the gauge on a table and shim as needed so that the remaining camber vial reads "0". Place a small dab of silicone glue in each end of the groove. Don't fill the entire groove.
Note that the graduations are slightly offset. The offsets are at opposite ends. Place the vial in the groove and push down into the silicone until it is at about the same height as the good vial. Be sure the graduations on the vial line up with the lines and numbers on the gauge. As you are doing this try to keep this vial at "0". This is done by pushing down gently on each end in succession and observing the degree reading. When the proper depth is reached be sure the vial reads "0".
Check it in 1/2 to 1 hour. If necessary readjust to read "0". Often the vial will sink slightly into the silicone while curing. If you wait too long you may not be able to readjust it. Leave the gauge undisturbed on the table for 24 hours to cure.
If BOTH camber vials are broken it will be necessary to independently level the gauge, using the bottom surface, before using the above procedure on both vials.
Place a very small dab of silicone in each end of the groove. Push the vial into place until it bottoms out. Be sure the graduations on the vial line up with the lines and numbers on the gauge. It is not necessary for the caster vial to ready "0" when installed. Allow to cure for 24 hours.
Small end vial:
Place the gauge on a level table. Place a small dab of silicone in the groove and push the vial into it. Adjust until it reads "0".