Check these things for me: How many holes are in the seat pan and what shape are they? Air cleaner: Is it a Vortex(cup on the side) or a Donaldson (oil cup on the bottom) How many holes in the hood? Early models had 2 holes in the hood to acess the priming cups in the head. Later hoods do not have this feature nor do the heads have priming cups. Start there. John