Pete, if you don't own a strobe timing light and a multimeter, it's time to buy them. A few years back Yamaha produced a batch of new advance governors at a reasonable price, but thanks at least in part to ebay profiteers with the ethics of ticket scalpers, they didn't last long. Mike's XS offers a Chinese repop, and I strongly recommend avoiding it. To inspect your advance governor, all you need is a multitester set on the ohm meter function to tell you when the points open. With the ignition off and turning the motor by hand, check the full retard spark (points opening) first, then clip the weights to the tabs and check the full advance position. Don't bother looking for NOS weights alone; the weights were offered only as part of the whole assembly.