Take the foot off your machine and take it with you to a sewing machine store. Most of the specialty sewing machine stores I've been to are combo sewing/vacuum machine stores (just so you'll know how to look it up in the yellow pages). All these stores seem to be the mom & pop variety, with casual atmosphere and friendly, helpful and KNOWLEDGABLE advice (not like your big chain stores who hire help that don't know crapola about what they're selling).