I have 3 TSDZ2 Mid Drives that I am parting out. Out of 4 sold in the past year or so 3 have been back for repairs. One unit 3 times. Is it rider error? Too hilly or too much weight for this area? Either way, they have not been a reliable unit & I am switching the owners over to Bafangs. I unit is located in the U.S. for cheap shipping & 2 units are located in Canada. Some units are developing gear whine, one has a software or sensor problem & one unit just flat stopped working. (Problem yet to be investigated) All these units have been in service for less than 12 months & most of them have only seen 2 or 300 miles at most. You can buy parts as needed or buy the whole defective unit as is. Full disclosure on each unit will be provided. All units have the Brass Gear & VLCD5 Display & been installed on Recumbent trikes ridden by oldsters. 4 New Blue Nylon Gears are also available.