Contour Enthusiasts Group Archives Forums Modifications Transaxle Clutch pics

If it glazed early on, it would have slipped over its life and caused that.

Also, if the flywheel wasn't surfaced correctly and the standoff distance of the pressure plate when bolted to the flywheel is too high, it will not apply full clamp pressure and cause that same issue.

There are sure to be specifications as to how much standoff distance the pressure plate mounting locations should have. If the pressure plate mounts flush to the surface of the flywheel without being on any raised-up portions, i.e. same plane as the flywheel friction surface, then a flywheel that was not surfaced or had a lowered friction area could be too far out for good clamp pressure.
Bottom line is it has to be in the right range for good clamp pressure.
If you did nothing else wrong, I'd check there first.
Try to get stock specs for this figure, and ask SPEC what they recommend since they provide the disc and the aftermarket PP.
They would know the ideal distance and then you can tell the machinist to make it right where it needs to be.