I had the same problem, after much trouble shooting, changing LNB, rfeceiver, etc. a Tech from the "okd school" asked me if Ihad "reset" the controller??????

Set the unit to stow and then turn off after it stows.

Set the elavation to "0 0"

Turn the ACU ON, then to OFF, (do this a couple of times)

Wait about a min. with ACU off.

Set your current elavation

Turn REceiver and ACU on.

(if you get no action or strange lights, turn to stow then off a couple of times, then try search mode again.\\This reset mine and works fine now.

(I would like to buy some old parts and "stuff" for my DBS for spares
if anyone knows of any.

Thanks, Max