My 617 primer pump is the original 25 years old, doesn't leak, never been used unless by the indy.

Why are they needed? If you fill the main filter when you change it, why would you ever need to use the pump? I tried mine to see if it worked and didn't know how to use it. You unscrew, lift, and pump, right? Mine wouldn't unscrew. I started to get some channel locks and use some persuassion but decided to leave well enough alone.
If I never use it, will it never leak or should I change it as a long trip precaution?

Charles