Dear Ron;

Okay the "set screw" is to position or center the pump. On the 216/235/261(s) It's the same I believe.

Tighten it up snug & then losen 1/4 turn. While holding it there, tighten the lock nut good.

Good luck, John M.......

John M., I.I. #3370

"There are no shortcuts to any place worth going". -Anon