For the RLs, there's a similar clamp somehwere on the positioner. I think you have to take off the access cover (4 screws on top), lift the door at the back edge slightly and release the catch. Then take the door off. Lift the R/W PCB in its screening box (middle of the back section of the drive) and flip it over towards the right side of the unit. Then examine the head positioner for a locking clamp and move it so as to lock the