I need to replace the pins in my door upper hinges on a 67 firebird Any advice on how to get the old pin out and the new one in. Specifically, the pin looks like it installs from the bottom. What keeps the pin from falling out. The old one looks like it was staked or something. And how about the brass bushings. Are they hard to get in and out. Any advice would be appreciated. Can the pins be replaced without removing the hinges? Thanks.............