Hammer nose bushings are easy to replace. All you need is a pin punch of the correct size for removal, and a center punch for installation.

The removed hammer is supported on a bench block or a slab of hardwood with a 1/4" hole. Use the pin pun to drive the old bushing out of the hammer. Replace hammer nose striker, install replacement bushing, and use the center punch to flare the end of the bushing to secure it. Make sure that the bushing ends do not stick out and scrape the frame as the hammer is worked.