Look in some used computer retailer if you can find a similar drive to replace your failing one.
You have more chances of finding what you need if it's 3.5" unit. Your chances are very slim if it's a 5.25" one. If it's an 8" unit, you only could find it in a display of a museum of computer technology.
Keep in mind that floppy drives are no longer manufactures and that it's the same for the floppies themselve.
