First you have to select the OTA antenna at teh Jack Wall plate (yes there is a wall plate, same as the winegard wall plate) if you see signals on the "Sur-Lock" with the wall plate set to cable someting is strange.
Now back down on teh gain on teh Sure lock and peak the signals.> This will not affect antenna gain.
Make sure there is actually a coax cable between the Wall plate and the TV.. This may connect to the rear of the Wall plate.
The crimp on connectors have a way of slipping off on that cable.
And last: I assume from the mention of HDMI which by the way has nothign to do with OTA reception that you have a newer "Wide screen" ATSC compatible TV... If your TV is analog only.. Problem identified.