Have you tried the prussian blue of machinist' dye suggested earlier? the taper of the splines may be the issue.
if you still have the old one, measure the thickness, and ID of the splines at the large and small ends and compare it to the new one. A local machinst may be able to hel you with the dimensions if needed

Might also just try a different brand from a local parts store. take your old one with you for comparison or look for an NOS one