said lead screw is provided with a key pin for engagement with {TAIL ~ a recess} provided on the screw lock member and for inhibiting said lead screw from rotation when said key pin is engaged with {HEAD ~ said recess} 
said lead screw is provided with a key pin for engagement with { TAIL ~ a recess } provided on the screw lock member and for inhibiting said lead screw from rotation when said key pin is engaged with { HEAD ~ said recess }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD