Buy some felt; some glue;and a sharp pair of scissors.
Felt replacement

I bought some self-adhesive felt and used some epoxy on loose weights on a set I had. Worked really well.

I used Elmer's Rubber Cement to glue new felt to my plastic pieces. It is very thick and does not soak into the felt like white glue.

I bought a decent set of plastic pieces from HOS that are weighted. The problem is that some of the pieces on the bottom felt is chipping away or the weights are becoming loose in the pieces. Does anyone have advice for this? The pieces are only a week old.
Thanks!
Like Trevor said, I'd try to get them replaced.
Failing that, Walmart sells sheets of stick-on felt that work well for this purpose. The more difficult question (IMO) is how to secure the weights. I've used regular Elmer's with some success but maybe Elmer's Rubber Cement, as suggested by chkmtk2wr, would be better.
I bought a decent set of plastic pieces from HOS that are weighted. The problem is that some of the pieces on the bottom felt is chipping away or the weights are becoming loose in the pieces. Does anyone have advice for this? The pieces are only a week old.
Thanks!