I've done a couple of them. As long as there is no need to repair or replace
the cone or detach it from the coil or spider (I think it's called), I
didn't have to shim the coil. The spider held it centered well enough that
as long as no lateral load was placed on the cone during the foam glue
setup, the air gap remained OK.

--
Paul Hovnanian
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A recent study found that women who carry a little extra weight
live longer than the men who mention it.