The adjustably displaceable frame member 17 is constituted by {TAIL ~ a flat bar member} 38 having a flat support surface and a right angle rear plate 39 spaced rearwardly of the forward edge of {HEAD ~ the flat support bar} 38 
The adjustably displaceable frame member 17 is constituted by { TAIL ~ a flat bar member } 38 having a flat support surface and a right angle rear plate 39 spaced rearwardly of the forward edge of { HEAD ~ the flat support bar } 38
OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL 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 HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH