Never have stalls. Ever. Had one today and haven't a clue what caused it. Regardless, despite attempts at gentle wiggles, the rod wasn't going to budge so I just left it alone on a cool back burner. The <<bad boy>> was locked. Two hours later, it was half drawn down. Came home from work and it was all down, drained.
Moral of the story? Avoid implosions. Leave the pot alone.