Read up on speakers (especially ARs) before you wreck something.
Cloth surrounds are not meant to be refoamed since they have no foam.
Buzz could be related to a deformed former usually caused by over driving the speaker or bad speaker seals.
One of the good reasons for not adding a ground that was not designed to be in the equipment because of some misguided thinking that the equipment would be safer.
Your expertise here and great practical knowledge of wood and it's characteristics before and after fiishes is a godsend for "wood" people.
This definitely should be a sticky.