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