Had a fine running 9.5 1973 model that lost spark on top cylinder. I pulled the fly wheel and found all of the stator plate screws loose. all else look fine. points and condensor look fine. i cleaned and reset the gap in all and reasymbled and still have no spark in the top cylinder the coils look brand new as well as the points. How do i check this flaw or just use the shot gun approach and change everything. Any sugestion would be appreciaited. The manual tell you how to change and check cleances, but gives no tests. Thanks....Robert