Square Baler Bearings and Gathering Wheel

Hello everyone,
This is my first post on the forum, however I'm a pretty regular follower.
My question is probably easy for some of you more experienced haymakers out there.
I bought a NH 311 last year and ran approx 15000 bales through it with almost no issues.
As I was preparing it for the upcoming season I got to wondering how often the plunger bearings should be replaced, is their a specific number of bales or just wait till they go out (I'd really rather not do that). Since I know little about the balers history I have no idea how many bales have been run through it.

I also have built a gathering wheel for the 311 I figured I'd share with y'all and see if there was any constructive criticism you could give me, sometimes the windrows are just a little wide for the pickup and I need all the help I can get. So I built this and am in the process of painting it.

Thanks in advance for the help and happy hay making to you all!

Square Baler Bearings and Gathering Wheel