Those fans usually have those problems a specially the later models most people just take the little clicker out of it and it is fine I think it was just a design flaw I don't know why they didn't keep The tilt knob on these.
Jordan U well I know eskie wolf has a grey one and it had the clicker taken out of it when he got it and he moved it up and down and seemed to stay it just didn't click. I had a blue one from the 70's and it had the clicker problem but us ally I would keep it in the middle and it was fine.
Iv never had this issue before. it may have been the clicker thing in there. iv seen people take the clickers out. and just use it that way (Eskie does that) iv done it with one of mine. and tighten the screw on thing and it seems to work.
Someone on the forums suggested that I grease it. I suppose that may work, but I think I'll go the route of removing it; that's free and I know it will work. I just would love to know why all of a sudden it would stop working like this..there doesn't appear to be any damage or defect.