Ken, Not to discount the other responses but I would suggest that first you should run a piece of cable from your power supply/splitter antenna connection on the power supply to the antenna and try to scan your TV. If there is no change AND you have full battery voltage at the fitting for the antenna, I would guess your antenna head needs to be replaced.
After the change over to digital, many folks found out RG59 is not the best cable for HD digital signals. Don't get me wrong, it does not need to be replaced but RG6 is better. Also some of the old style "F" connectors are not the best and attenuate the signal dramatically.(It could be RG58 and RG8, I forgot the numbers.)
If your connectors are the old style crimp on it may help to bite the bullet and buy a coax cable cutter/stripper and a compression connector tool and connectors and replace all of them.
I am assuming your TV set is a flat panel with scan and signal strength built in. Most now have signal strength meters built in and that is how I align mine. You can also look at any antennas in your neighborhood and aim yours the same way.