I'm not sure why there's zerks on these spindles because I think the bearings might be sealed as well. One thing I know is I've had several spindles fail in 4 years, maybe not that high of a casualty considering all the rocks I've hit so yeah, all the failures weren't the bearings, cracked housings etc.
Always bugs me that they do that. I think forcing grease on a sealed bearing adds to the chance of it spinning in the housing. Which is how my previous set of spindles failed. I don't recall if the bearings were open or not.