A large fruit juicer was being moved and it tipped over. Inspection revealed that the two rear caster wheels were “frozen”. In fact, flats had been worn on them from sliding the machine while the two rear wheels would not rotate. Corrosion (i.e. rusting) of the galvanized steel axel and galvanized axel “sleeve” caused seizing of the wheel. Basically, the rust packed the axel hub to the point that rotation was impossible. If these wheels had rotated, the machine would not have tipped over, and the injury would not have occured A better choice would have been casters with stainless steel axel parts. These are readily available.