From your comments about the green colored corrosion, I suspect you equipment has had some hard usage or bad storage and may have many points that have corroded and now cause bad or no contact where needed. Is the antenna securely screwed into its contacts on the transmitter? Are the battery terminals inside the transmitter clean and shinney? Are either of the battery wires inside the transmitter stiff or corroded (black wire disease could be present if old NiCads were left in the transmitter while it was stored and the cells ruptured or leaked). The advice to send it back to the manufacturer or a service center sound good.