we put a 12 volt generator off a RC 88 DSL on our 66 gas in 1988 we left the 6volt starter on and it lasted for years. Then when we broke a spring after years of use they only seemed to last a year or so. Finally we had our starter guy rebuild our starter completly &amp; pt 12 volt guts in it. Not a problem sence. I don't know maybe the springs are not as good of quality as they used to be. but you seem to have the same problem as we did.      We are very happy with ours now it all looks factory stock unless you look very close at the delco tag on the generator that reads 12volt.