Consider attending a Glock Sport Shooting Foundation match in your area. Not only do you get to meet, greet and shoot with a bunch of Glock owners, they have certified armourers in attendance to do exactly what you were posting about. I went to my first one years ago and handed over my G21 to one of the guys. He took it apart, looked it over, then asked me "Has this seen a lot of heavy use?". I answered "yes, it's my IPSC gun". He proceeded to replace a whole bunch of parts. Apart from the match fee, and GSSF membership, it was a freebie!
Go to
Glock Sport Shooting Foundation for more info.

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CCW permit holder for Utah, Pennsylvannia, Maine and New Hampshire. I can carry in your country but not my own.