On 18 Aug 2004, Greg Taylor wrote in
:

Obviously if the foam is deteriorated, and I agree that is often
the case, it should be replaced.

Can one buy replacement foam inserts for an SM58 windscreen?

I have a 58 that was sounding worse and worse over the years. Finally I
took the screen off and found that the foam inside had disintegrated
into a gummy, putty-like mass and wasn't letting sound pass through. I
scraped it out and the mic sounded like new. Since then I've just
popped a cheap foam windscreen over the metal ball.