I have an Interarms PPK/S purchased new in 1981. Lately, after every third or fourth round, the gun decocks and the ssafety is engaged all by itself. I spoke with several of the local gunstores with no real help. They all offered to send it to Smith and Wesson for repair. Smith said that since it is Interarms manufacture, they can not repair it. Are there any suggestions that you can make to repair it myself ?