TEC-9
Did it fail to fire? Fail to Eject? Fail to disconnect between trigger pulls or just start to come apart in your hand?
I know someone who has one, and he keeps tools in the carry case to tighten the screws before shooting it and any time he's taking a break from shooting it.
Fortunately he's done enough work to the action that it now reliabiliy feeds, fires and ejects 1 round per trigger pull.