I had another attempt at repairing my aerial unit, this time at my work so I stripped off the large cog that drives the toothed strip, the toothed strip and degreased them, then I used an airline to clean off the rest. I cleaned up internal channel where toothed strip runs and surrounding areas. I greased it all up with an awful lot of fresh grease then reassembled. I attempted to fit a little spring between the strip housing and plastic cover (fitting over long screw) plate but it would not then fit so spring was then removed.
Upon refitting, the aerial worked... once. Good thing is now it is very quiet when the motor operates but the toothed strip keeps popping off.
Any ideas why? Can anyone provide a technical drawing or detailed pictures that I could use for reference? U could buy one from Amazon for £25 but I'm tighter than two coats of paint and sure I can fix this, I don't like to be beaten.