Been down this road before on this forum. The contender screws are standard size (#8-32) and available at any hardware store. The Encore on the other hand are #8-40 which is a commercial machine style (found on lots of sewing machines). No one has found a good source for buying these in small quantities at longer than normal length, or if they have they haven't posted it. If you need standard length, you can get them from TC or Brownells, I got a couple from a sewing machine manufacturer (had to get some for a carpet binder and just had them send me 4 extras 2" long). try searching this post for the topic "encore screws" and you'll see we came up with a couple places but none panned out.
Bill