[bobcowan]

Temperature changes are your friend. Put the dipstick in the freezer for about an hour or so. Put a tube of silicone selanat in there, too.

When it's good and cold, heat the front cover around the hole with a torch, spread the heat around but get it pretty warm.

Take the tube and silicone out of the freezer, and put a little bit of sealant. Don't touch the tube with you hands, it will warm up too much.

Assemble quickly, and it should go right together.