Gear boxes could be a problem - last I heard they were not available through regular parts but I seem to recall there is a source - just have to find it. If the cart is stored outside and water let stand in the tube it will get into the box and ruin the lower bearing and then eventually the gearbox. We had the lower seal go out and could not get the auger off the gearbox shaft without destroying the gearbox so we just put a grease zerk and pumped the box full of grease till it came out the bad seal around the vertical auger. Ran it that way quite a few tears till we sold it at a farm sale and was still working fine then. Just gave several shots of grease when we greased the rest of the machine and forced some grease out so the grease would keep corn fines out of the gearbox.

Replacement gera boxes are pricey if I remember - something to check out for sure.

John