I'm now a happy guy, 3 miles down the road with bugs in my teeth! The Grubbie 4G that I bought must have been manufacuctued on a Friday afternoon but, is now running sweet.
On the clutch problem: Mine came out of the box with the clutch bearing pretty much welded to the bell. I brought the bell and bushing to a machine shop and had them put a bit of a bevel on the bell and turned the bushing down so it would turn freely. I found that when you install it, torque the retaining bolt down, the bell was actually becoming one with the bushing/crankshaft. (crappy design). The fix is to add small washers to the point where when you tighten the retaining bolt down, the bell still is freewheeling. (see pic).
The one-way bearing failure at the one mile mark was fixed by the JB Weld suggested by the gal at bicycle-motors.
At any rate, I'm now a happy camper and am tweeking and fine-tuning the build.
Barry