[mrnoble]

We had the same problem and contacted VexPro. There was supposed to be a locktite type adhesive shipped with the gearbox that was not included. They shipped us new shafts and adhesive, along with improved gears for the encoder shaft, which we also have had trouble with. They (Paul, I think) have posted on CD about these problems earlier and have been nothing but up front and helpful. Give them a call tomorrow.