Building Kit car

Hello All,
Building a VW based 70s kit cart with 11 inch electric motor. Search for Flywheel balancing gave me this site with DIY flywheel balancing project.

Learned to use a MIG welder for the frame work and for building small parts. Also have made molds and vacuum bagging for carbon/Kevlar/epoxy composite parts.

Need help with balancing 9 inch VW/Porsche flywheel. Can't find a shop with the required small mandrel, have been turned down by everyone so far.
Not sure why.

Thanks-