I would contact HB C/S and see if you can purchase that from them - or see if they will repair it at a reasonable cost, since I don't know that total unit dis-assembly would be required.
1.800.633.1468
(Monday - Friday 8:00 a.m. to 4:30 p.m. Central Standard Time)
Heck I would love a non-working unit myself just for spare parts and to have a look around at the marvelous little device!
Robert