My 1978 Honda NC 50 Express carb will not shut off fuel when filled. I ordered a new float needle valve, a KL 4612 that also included a tiny spring clip(?) The valve it self does not have the same milled portion at the bottom of the valve the old one does and it will not fit into the plastic groove of thee float. The valve did not come with instructions so I had to guess how it was to fit. I may be doing it wrong,or it may be the wrong part altogether. Has anyone replaced their valve with this new type valve and got it to work? Thanks for your help in this matter.