Penton Petcock parts needed

[ktmkirk]

It seems that I'm losing the right side little rubber handle peice off              of the fuel petcock on several of my Pentons. Can I get just the black                  plastic/rubber piece that goes over the actual handle peice?  The                  peice I'm missing has a "Z "at the end and says "Italy" in the handle                  section, some of the other ones are more plain looking.  Is their                  reason that only the right sides keep coming off....Kirk Sessions