Here is an observation on my 2008, as well as my friends 2010 , both Montana Fifth Wheels. Grease is a wonderful thing unfortunately the 2008 of mine has only the one zerk to lube the top gears. The 2010 has two perks one for the top gears , and one for the long worm gear.
The 2010 was also laboring, mine has always ran decent, not great, but still on the original motor. The 2010 was nearly coming to a stop , well the gears were pretty dry, greased up both zerks, and it runs like a champ. That could be your biggest problem.