Crash: I was involved with the Illinois State Police selection process when they retired their Colt Python 357s in favor of the S&W Model 39, the single stack magazine version of your Model 59. Many thousands of rounds were fired through each test pistol without any breakage to the sears. The only problems we found were that the pistol came in only 9mm and not 38 Super, which was the preferred cartridge by the ISP and that some simply would not feed hollow-points. If yours does, then enjoy the pistol, there is nothing wrong with it.
As for the Sterling: Got one! Shoot it once in a while. At least once in every clipful she goes full auto for two or sometimes 3 shots. I haven't found a place to get it repaired and my local gunsmiths don't know anything about them, so I include the full auto possibility in my training with it. Mine has never jammed on me, so going full auto once in a clipful doesn't bother me. If yours has feeding problems you probably need a new magazine and those are availalbe through the Shotgun News. I will grant you that Sterlings, Jennings and some of the other 22s aren't quality handguns but if you can get one to work reliably they become inexpensive insurance. Hope this helps. Mikey.