Be careful when you pull the seals and they will have a number on them. My trailer has bearing buddies OE. I don't know about the older ones. If someone has kept it greased everything may be ok. Unfortunately the only way you know is to pull the seals , pop the bearings out , clean them off and look at the condition of the bearing and race. Shiny , smooth , and no pitts or grooves is good. Repack with a bearing grease. I use Mobil 1 Synthetic. Tighten snugly, spinning the hub as you tighten, don't over tighten. Once the nut is snug, back off slightly and install a new cotter key. Done and you have peace of mind.