That is the problem,a lot of the older bows do not have the riser cleared out for the arrow enough.The overdraw may be causing some of the problem as well.Some of the older bows that I have tuned for people need to be shortened a little,can't say without seeing the bow.Vanes should clear on all bows so keep tinkering and find out what is causing the problem.

Muzzyman has a good suggestion,the cock vane out should do the trick.