It can never be fixed. I heard it from a guy at the gun shop who was wearing black BDUs and a tactical fanny pack, so he must know. Judging from the responses above, including changing the wrong parts, etc., he's probably right.
You should quit shooting Glocks.
Pigeon chess - "having a pointless debate with somebody utterly ignorant of the subject matter, but standing on a dogmatic position that cannot be moved with any amount of education or logic, but who always proclaims victory."