Question: Antenna height for reception

My antenna is 40' and the top is about 750' above sea level. It is amplified, vhf & uhf, top of the line outdoor type with rotor. There is an additional amplifier in the house, a skywalker with variable gain. The FM is off at the antenna amplifier. All possible stations are either mostly north or straight south. There are hills surrounding me that top at about 910'. Distance to the stations is less than 75 miles.

I get one station that is 70+ miles to the south but none to the north. Station info south:

We get KOLR with occupational breakup.
On very rare occasion, we will get the other stations to the south of us that are located very near this station.

Station info North:

My question is: Will adding extra height to my antenna help? If so, how much height should I add?