the pickup and the shaft should never move to close the gap even when it advances, your distributor bushings are bad, you can buy stock replacements for about $40 for a small block if thats what you have
Actually they all move some, due to the what amounts to a fairly poor design of the advance plate. I ALWAYS take one of those hand operated vacuum pumps and check the clearance both with and without vacuum.
But it could be what people have mentioned---loose bushings, bent shaft, etc. "Remanufactured" is an insult to us consumers and has been for a very long time
The other problem with a "store bought" rebuilt is that you have no way of knowing what you really have, especially with something that matters, like a carb or distributor. On top of not knowing the quality of the workmanship, you don't know what advance curve is in the thing, unless you actually check it.
