Try slicking them up with some parafin wax or some silicon spray.

Been there, done that. I can't spray directly into the sled (I'd get it onto the contacts, which would be a Bad Thing), but I've put a little lubricant onto the bumps with my fingertip. It helps a bit for just a couple of insertions, then it rubs off. And it makes the Empeg oily- and since I move the Empeg amongst three different indoor locations, an oily Empeg is also a Bad Thing.

I've got some other things I'm going to try today. I'll let you know how it works out.

Tony Fabris
Empeg #144