Well, you are down to three possibilities. Improper(or worn) linkage adjustment, bad or incorrect nss switch, or the part in your tranny that activates the switch - I think tactrans (Terry) called it a VB-1. IMO, HIGHLY unlikely to be the transmision's internal part. Terry, feel free to correct me though.... I think it is going to be linkage adjustment or nss. To first take the linkage adjustment out of the equation, I would disconnect the linkage rod at the trans and put the trans in park with your hand - lever all the way to the rear I believe. (put the connector back on the switch) Then see if it will turn over. If it does, then you need to examine/adjust/repair your linkage until it engages park properly. If it doesn't turn over, I would suggest your new nss is faulty or installed incorrectly. With an ohmmeter, you should read zero ohms from centre pin to the small round steel ball on the other side of the switch.