after removing the tappets from my 899 cinq i noticed a retaining clip holding the two parts of the tappet together. Some of them are broken but the two cylinders remain together is this clip esential or is it merely to stop them falling apart during manufacture. Im having a hell of a time describing them to the local motor factor as they are not the same as the ones in the haynes manual which only show the tappet as a whole single drum not one within the other. help?