Invisible zipper foot for a Pfaff Hobby 1042?

Oooh my first post after a year of lurking

I am having a horrible time getting a coates zipper foot to attach, even the gentleman at the sewing shop couldn't help!  Apparently there isn't a specific invisible zipper foot for this model.  Does anyone know of a universal inv.zipper foot that might be worth trying? Or any tricks to finagling a coats plastic foot onto this machine?  As satisfying as it was to finally complete a 20 inch hand-sewn invisible zipper...I'd like to be able to cheat!

Your machine is only a couple years old so you should be able to find an invisible zipper foot for it.  Those plastic Coates zipper feet never work well so it's a good thing you didn't buy it. 
I would find a local sewing machine dealer- not just a sewing shop.  They should be able to find you one to fit your machine.  To be sure it'll fit your machine, I would bring in one of the feet from your Pfaff to help with finding the correct one.