I'm taking the drift boat from B-ham to the E-burg on Saturday and I want to check the bearings, however, not sure how. I remember as a kid my dad unscrewing a dust cap and packing grease into a buddy bearing, however, my hub doesn't look anything like this. In the center is a rubber plug (I'm assuming it's a plug), which I'm not sure if you simply pry out or not?! Its a Zieman trailer; which I searched online and can't find squat. Anyone have some guidance for me? At best my trailer has seen less than 2000 miles of travel over the 7-years I've owned.