I own a Singer Merritt 1812 sewing machine that originally came with 18 interchangeable cams for special stitches. I only have one of these cams, numbered 276301. It is a keyhole type cam. Here are the questions: 1. Do all singer keyhole type cams fit this machine (I have seen several for sale on eBay that have a similar numbering system? 2. Are Simanco Flexi Stitch keyhole cams compatible with my machine? 3. Does anyone know of a reliable Canadian source for parts and accessories for this machine?