Are you sure the jack in question has more travel? If it does, maybe you should check the oil in the reservoir. (DextronIII, if yours is like mine, a 2001 gasser)
The front jacks, as you say, work together. The rear jacks also come down together, but then they are the ones that level the coach and the fronts then follow along. It's called by some, the "slave" system. Rears, level, fronts follow along.
I try to avoid extending the jacks fully. When faced with that, I put the square plastic spacers used for the tires under the jack "foots". Of course, the plastic squares are, by that time, under the tires if leveling calls for them.
Access the PowerGearUSA website. LOTS of info, lots of downloads, and maybe a real live human at the other end of the 1-800 number.