Many years ago--you could buy a new zipper at a luggage shop, and buy a bag made of similar material to the old one, or have a bag made at nominal cost, and take both to the local shoe repair shop, or harness maker, and have him sew in the new zipper, and sew up a bag for you---but not now, due to the fact those guys are long dead, and we live in a throw-away society! Maybe, you can still buy a ready made zipper.
That said, can you find the model and serial numbers, and take them to a dealer, and possibly order the bag?

Call Bill Rodger I know you have chipper not tiller Bill your best help.

I can supply parts to repair your tiller. Keep in mind that supporting me with your purchases when you can will keep the site going. Email vppinc@cox.net or call toll free 1-800-609-5110. Bill Rodgers.

Thanks Guys. I will see what i can find