I have a 2006 Pontiac GTO with a 6.0/LS2 motor with a 6-speed manual trans. Every once in a while (1 to 2 times per day on a normal driving day) when shifting from 1st to 2nd gear, it will not go into 2nd gear without double-clutching the trans. The problem is very intermittent and the dealership keeps sending it home saying they "cannot duplicate" the problem. Any ideas??