hope i'm not jinxing myself here, but i think i've FINALLY resolved all the alton starter issues with my Mk2. seems there's a small percentage of us that have alton starter interface problems. personally, i think it's some sort of tolerance stack up between the norton components and the alton parts and assembly. mine seems to be just outside the window of being compatible. after 18 months, two woodruff key failures, a dozen sets of polyurethane shear pins, all seems good. the "Yves fix" is working perfectly but i had to go with SIX shear pins on the starter/sprag clutch interface assembly. a couple weeks now, several dozen starts, and not so much as a hic-cup. for the shear pins, i used an, off the shelf stock from McMaster-Carr, p/n 2656T58, 10mm polyurethane rubber rod, cut into 12mm long pins. as a redundant locking feature, also used a serrated bellville spring lock washer under the crank lock nut, p/n 90895A216, although with the Yves fix, it's really not necessary. if i have any further problems with the starter, i'm out of ideas. HOPEFULLY i've put this issue to bed and i can get back to some serious riding once again.