Why Experience Matters With a Pool Contractor: Jandy valve grease port replacement question.

I was replacing the o-rings on my Jandy valves because they seemed to be leaking air. I discovered that one valve had the grease port plugged. Perhaps it broke and someone was looking for a a cheap fix.

Amazon has replacements for $23. Should I replace it?

What is the correct use of grease ports? Give them a turn every month or so or what?

Thanks for any advice!