Got tired of loosing screws on a fold-up plastic camping table. Decided to 'Lock-Tight' the metal screws to their corresponding nuts. Left it overnight in the garage and the next day it lay on the floor in hundreds of pieces. There was concentric circular cracks 1 to ~6 inches from every bolt with radial cracks about 45degrees around each, so lots of pie slice pieces and large chunks with 6 inch arcs or holes....
What was the plastic? A wild guess from a great distance would be ESC.
Many kinds of contaminants can lead to the long term degradation of the material used to make these handles. I worked in the aerospace industry and synthetic turbo engine oil was one of the worst for this. Just a light film from hands on anything plastic, would cause them to become brittle within a few months.
I never had a brittle handle on the 34401A but I had a few very brittle frames on the back and one front window.
There are lots of polymer resistance charts online if you need to check whether any particular substances are likely to be problematic.
Doesn't cover every case, though. I had an issue with polyurethane products rotting at a turkey farm a while back. Was traced to the ammonia compounds released from the manure. That wasn't on the list.
Many kinds of contaminants can lead to the long term degradation of the material used to make these handles. I worked in the aerospace industry and synthetic turbo engine oil was one of the worst for this. Just a light film from hands on anything plastic, would cause them to become brittle within a few months.
Wow that's not one that would have occurred to me. I wonder if synthetic automotive oil does the same? I'm going to have to be more careful.