[surfwooder]

After buying a E89 Z4 2009 model, I've found the top system to be basically operated by hydraulics both in up and down mode. You have already done my first guess of the root of the problem, changing those salmon relays, on the hydraulic unit. Those relays provide full battery current to the electric pump motor, and control the direction of rotation of the motor for up or down motion. Within the top structure there are a number of microswitches, and Hall Sensor proximity sensors. Each of these sensor inhibit, or stop the top from opening or closing. The only actual top internal electric motor is in the bow of the top where the two claws move into position to lock the top to the upper windshield. The circuit card that controls the top is the Convertible Top Control Card. It is also located in the trunk in the next partitioned compartment next to where the hydraulic unit is located (to the right side) to get to it you'll have to remove the truck bottom plates to the right rear tire well. I noted in the video, it only took a light touch to get the top to move to the down position. To me this indicates a possible sensor problem like a microswitch out of adjustment. I'd also check the fluid level while the top is fully up and locked to the windshield. Remove the brass screw on top of the reservoir, and fill if low. Be sure to have the proper fluid to add if low. The top should move to fully up, and fully stowed in 22 seconds each way. If you look at the wiring going from the batteries main buss bar two red wires go directly to the salmon relays plugs. These wires feed full battery current to both relays. The selection of the making of contacts in these relays come from the CTM based on the direction the top is to take. It would be a benefit to measure the amps during top up and top down function to test the motors load value to the system. If you bought the car used, you may want to look into any history of the top and problems it may have had. Hydraulics units are very sensitive to dirt in the systems clogging valves within the control unit. So if you open the unit in any way be sure to cap any open lines.