No help from them.........they currently don't have any, are in the middle of a re-design ( I can see why) and may have something by November.
The service department's suggestion was to phone around music stores to see if any store had an extra one that had been shipped.
I guess he has more time than I do !
Thanks again...........
Well, that's sad. However it should be pretty easy to fabricate one yourself.
I'd tape a letter sized peice of paper over the hole with some 'magic tape' and then use the SIDE of a pencil tip to buffer/trace the edges of the opening, and then remove the paper, cut it out close, and then transfer it to (by taping it to the surface of) a piece of masonite (scraps can be had at most hardware stores for a few dollars), and using a t-square, score the straight edges, and then use either a coping saw and/or file to put a nice radius on the corners, constantly checking to make sure it fits the opening in the back of the U-bass, and when all done, you can get small Neodymium magnets like 10/$1 at places like suntekstore.com or parts-express.com, and with a dab of either hot-glue or super-glue, fix the magnets to the 'door', and then voila, snap it back onto the instrument in question.
In a pinch you could also use material from a butter tub lid or tupper-ware as the 'door' material.
If it were me, in your place with this info from Kala, I would probably fabricate a replacement. Once you have all the materials, if you go really SLOW, it should not take more than an hour or two...unless you have no comfort level with tools and/or working with your hands...