I recently bought a used Glock 36 from a dealer. The pistol appears to have had little use but I am having a problem with the slide locking back. The dealer replaced the slide latch but the problem persists. Locks back with both mags and 2 different loads. 230 FMJ and 230 HP. The pistol was clean and lubed. Also tried different holds. The Glock factory rep will be here in a couple of weeks but I am looking for some ideas.