These 4" Plastic wheels, PN 3205257, for the drum handle mounting point were on Mortarman 120's built prior to Jan 2018. A new upgraded full size wheel kit is now available to replace these 4" wheels. It is available for purchase here on this website
IMER Mortarman 120 Plus Mixer PN 3205257 - Pre 2018 MM 120 - 4" Wheel
SKU: 3205257