There is a Janome dealer in Tulsa, at 51st and Sheridan. (I have NOT had good service with them and wouldn't recommend.)
There is also a Babylock Dealer (SewB Inn)and a small shop that has several different lines- he fixes everything and I think he sells Juki (for sure) and Necchi and Pfaffs. If you PM me tomorrow, I'll get you more specific info.
There is no sewing machine shop in Bartlesville, unless it's brand new. When I lived there, I had to come to Tulsa for repairs.