
I looked that part up and it doesn't match mine.
The two green boards i have on mine are marked as follows:
55-0302-00 (smaller of the two boards) HAPP website calls it a "TRACKBALL USB & PS/2 PCB SATELLITE PCB (B)"
55-0301-00 (larger of the two with more plugs on it) HAPP website calls it a "TRACKBALL USB & PS/2 MAIN PCB (A) PCB "
Which one do you suppose controls the vertical movement? It appears that when i move the tracball vertically, the wheel that rotates is the one "attached" to the larger board.