RedRich Hi,
The re-gauge on the 071 is nearly identical to the 181, I used P4 Black Beetle NS 14mm wheel sets. These came on
2mm axles. The axles where changed for 2mm bright steel rod filled down to allow a BB of 19.88mm. The plastic gears are removed from the
original and pushed onto the new axles (off centre) and a drop of thread lock. I have not required spacers or any removal of plastic!