"F. George McDuffee" wrote in
message ...

At normal speeds and putting two small weights, one inside
and one on the outside of the rim may be all you need.
http://www.amazon.com/Bullseye-Level.../dp/B00466L2GU


The general solution is four equal weights, in pairs spaced
equidistantly on both sides of the light spot, which is the place the
bubble moves toward. Move them closer together to increase their
effect, further apart to decrease it. As "F" said put one of each pair
on the outside of the rim and the other one opposite it on the inside
so they don't change the dynamic balance.
-jsw