I have to say that a shear pin does seem to be a fairly crude method of controlling mechanical damage, it has been used to protect propellers on marine engines for many years, but with the Grosset starter it is all we have so we have to live with it. When I was having my Grosset starter fitted last year (by Francois) it was a bit of a joke from Francois that a few users had found it a great solution to install a nail of the correct size to avoid any further problems, I don’t think it amused Francois that much though.