They do not make a shim for the 280 needle. I think only up to 250. If using a 280 needle, you will have to build up the needle deflector shim to accommodate the 280, needle. You want to put needle in once you have the shim is widen. Remove the throat plate, feet and feed dog. I would then by hand turn the wheel lowering the needle and see how it is in relation to the hook. Touching? Or deflecting? If so you need more distance rings.
glenn