Hey, sorry its been awhile. Its an 1981 Tucker 542 (i believe).
How would I rebuild them? Aren't they a sealed bearing?
Semi- sealed until the backing plate departs.
I really don't know of an effective way to rebuild a tucker roller.
You would need to replace the balls, and install the axle into the roller, maybe a press? Dunno, that would proly score the race.
Usually, as I've found out , once the backing plate separates, you loose a coupla balls, it's only a matter of time until the roller destructs, the outer race falls off, and if you don't IMMEDIATELY remove the axle core from the track, you WILL have a de-rail. Then you have to re-rail before moving very far or risk serious damage to the entire pontoon/track.
Usually in a storm, at night, and oh shit I fergot the snoshoes.