The running surfaces of the wheels become worn during operation. This reduces the diameter of the wheels.

   Unscrew the self-locking nuts (4x).

   From size 160: Remove the plastic washers (4x).

   Remove the buffer plate.

   Measure the diameter of the wheel at multiple points over the width of the wheel.

   The diameter may not be smaller than is specified in the table.

If the diameter is smaller, the wheel must be replaced. See Disassembling the powered wheel.