You can just use a simple method whic utilizes lift arms and small elastic bands. I attach the lift arm to a pivot point, and insert the track hub on one end. On the other end of the lift arm, past the pivot point I insert an elastic band atached to a secure location, to force the other end of the lift arm down, that being the end containing the track hub, that the track will flow along. When the section of track that the track hub governs goes over an obstacle, it will force that end of the liftarm up, pulling against the elastic band which will try to pull its end of the liftarm back up which will lower the other end, the end contains the track hub, to its original position. Sorry if this confused you, and I would insert a picture but all my pictures are to large for the downloaded to handle.