I was removing the 8 bolts that hold a Tokheim 850 visigauge together and making good progress. When I started on number 8, the entire bottom of the outside glass cylinder cracked all the way around and two pieces shot out across my work bench. About 3 minutes later, two shards of glass popped straight up from the bottom ring that was still anchored in the white sealant. I have heard of this happening to a visible cylinder and now I know that it can happen to a visigauge cylinder as well. The mistake was far less costly than doing the same thing on a visible cylinder.
Joe