Replacing the wheels did not look that difficult so I googled my model and found the Appliancepartspros. They assisted me in finding the appropriate numbers in order to find the parts and the wheel kit was available. The kit contains all eight wheels for the bottom rack, and I replaced the two that fell off. Just a heads up, put the wheel on the axle before mounting it to the rack, it does not work the other way around! Now I have replacement wheels for the rest of the rack and future repairs.
Thanks for your assist.
Tom