John's got ya' covered.

If you do try my "trick" for removing the spring, be sure to clean out any gunk in the spring hole. It can build up over time. You want your punch or bit to go in as much as possible and be an exact fit.

Soaking the spring/base in penetrating oil overnight will help.

And, of course, use a block of wood or brass hammer to tap the base, not a regular hammer like in my photo!