Try seaming the outer edge of the new seal off to trim a couple of thou off of it. Ensure there are no rough edges in the port where the seal goes in as well.
Grease up the port with a thin film to ease it in better and straight.

95 Contour GL. Bought new. BAT Sway Bars/Pioneer CD/Koni Rear Struts/Mobil Fluids. Looking for 15" alloy rims-PM me. 180,500km's so far.