I am working on a 1973 446 Tractor Serial # 9678679 with a Onan 170-2968 engine. I did a tear down of this tractor, cleaned , repaired and painted it. During the reassemble I noticed the ( Borg Warner Hyd. pump) elbow fitting coming from the rear cover seamed loose, it rotated easily. Well it came apart and I replaced the O ring (1" od x .100 thick) that was worn, thinking that was the problem I greased it up and put it back together. It still rotates but not as much. My question to all is, what is supposed to hold this together and am I missing something?