Pat:
While it is possible that the weights are not well balanced, it should not be enough to make a difference. When you have a look at the weights it seems that they are all cast in a similar mould - they all look as rough as each other. Some people recommend taking the weights out, polishing, drilling them out and filling with lead to make them heavier - I'm not sure this is necessary.
Something is making your govenor rack bind, it could be as simple as a slightly bent rod, or as complicated (not really!!!!) as a dropped pin on the govenor wheel.
Give me a call if you can't find the culprit.
cujet - I used to be a big fan of changing the springs to longer and softe ones, since I have started using the mod kit on all my engines it seems to be no longer necessary - I'm thinking that the "straight line" spring and bolt arrangement helps a lot.
John F.