I have a pivot head like the one in the picture, but I can't get it to stay on because the inner spline pushes in when the pivot head is pushed onto it. Previous owner drilled a hole through the inner spline and had the arm stay on with a screw through the whole assembly, but it won't put any tension on the arm, so the wiper is just barely resting on the windshield.
Are there any set-screw pivot heads around?