Crumbling implies the solvent destroying the polymer bonds. This happens when using chlorinated solvents on plastics. Had a 1975 AMC Pacer—worst car ever made, but that's another topic—and the door panels were one-piece molded plastic, and they were coming loose. The mechanic used some thread lock that had something in it that caused crumbling. When I picked the car up, the panel was not only loose, but destroyed with cracks radiating from every screw. They ordered a new panel, and par for the course, when it came in, was for the wrong door. I fixed lawnmowers in my garage many moons ago and had parts cleaner (chlorinated solvent). I broke a jar with some oil in it and used the solvent to clean it up. When I was sweeping it into a plastic dust pan with a plastic-bodied brush, the brush fell to pieces in my hand. Tamiya glue is ethyl acetate and is not chlorinated as far as I know.