I have a 1981 Mercury 7.5hp and the cap was missing on the end of the tiller handle so I ordered an OEM cap. I noticed the end cap is threaded but there is nothing to screw it onto and I do not see any screws on the parts diagram for this engine. Can someone advise me what I am missing and what is screws onto? I don't think I should have to buy another used handle to fix this. Thanks