Hi. I have a D7 17A-5660 (+-) . It has locks on the greasable track tightner. They go over the shaft and are U shaped with grooves in them so they hold the tightner in place and are held with a gear clamp . My problem is I have lost them off one side of my machine and I want to replace them but none of my parts books even shows them. I have never even seen them on a machine before. Any ideas?