Numrich Gun Parts. http://www.e-gunparts.com/ is a good place to start. I haven't had a need for any spare parts other than extra mags and spare white dot inserts for the sights. The only thing that's gone south on my PSP is one plastic insert in my rear sight. HK sent me one under warranty. Someone else may be aware of weak points, I just haven't found any on my 2 P7s. The design has been around for a while and seems to have held up just fine. Spring set maybe? Perhaps a spare firing pin?