I destroyed one of my cobs by smoking it too hot. By the time the outside was completely rimmed in black, the shank pulled free of the bowl.
On another (both were MMs), I lost the plastic band around the shank, causing the stem to no longer fit tight enough. I probably shouldn't have removed the stem while hot, and when I attempted to glue it with Gorrilla glue, there was a toxic taste.
Why the hell are those dammed MM plastic fittings necessary anyway? I've got briars with stems which fit directly into the shank without further ado!