The tines 38 are {HEAD ~ solid, rigid structures} in {TAIL ~ the embodiment} shown in FIGS 2 and 4, but may be brushes or a similar, somewhat flexible structure which will effectively dislodge obstructions which blind the screen 30 
in
The tines 38 are { HEAD ~ solid , rigid structures } in { TAIL ~ the embodiment } shown in FIGS 2 and 4 , but may be brushes or a similar , somewhat flexible structure which will effectively dislodge obstructions which blind the screen 30
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL 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 OTH OTH OTH OTH OTH OTH OTH