wherein {HEAD ~ said step} of installing {TAIL ~ said circuit board} includes a step of mounting said circuit board on said rear tray 
of installing
wherein { HEAD ~ said step } of installing { TAIL ~ said circuit board } includes a step of mounting said circuit board on said rear tray
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH