Cut away the remains of the old felt gasket from the rims of the lid and base with the razor edge of a utility knife.
Dip a small sponge in acetone or rubbing alcohol with rubber glove-covered hands. Wipe down both rims with the sponge.
Scrape the rim surfaces with a grill scraper and brush. Reapply the acetone or alcohol with the sponge to keep the rim surfaces saturated.
Wait for 30 minutes after the rims are cleaned to allow the cleaning chemical to evaporate completely.
Spray a light coat of a multipurpose adhesive directly onto the clean dry rim to increase the adhesion of the felt gaskets. As the felt gaskets already have an adhesive backing, the additional adhesive is not necessary.
Pull the paper backing off the felt gaskets and press them onto the rim of the lid and base with the adhesive side toward the rim. Curve each gasket to fit the shape of each rim, but avoid stretching the felt material.
Trim the excess length from the gaskets so each rim is covered in a single layer of felt.
Lower the lid down onto the base so the two felt gaskets are sandwiched together under the weight of the lid. Wait for 24 hours so the adhesive is fully cured before you use the Big Green Egg again.