I have three sets of doors by US plywood. The pins are 5/16 by 51/4 long. The top pivot pin looks like the Fenestra pin and spring. the bottom slide pin is threaded at the bottom of the pin with the nylon peice measureshole size is 3/16, the ring is 5/8, and the end is 3/8. I am not finding the replacment nylon for the bottom end. can you help? Thanks