I also use a Reese 16k slider. The first problem I had was I installed the pins backwards (the 4 pins that hold the hitch to the rails). The pins have to face "out" with the clips on the outside of the rails. I thought by having the pins on the inside of the rails they would be more secure from prying fingers, but the hitch will not slide. Then I sprayed the rollers and other moving parts liberally with Safariland Break Free CLP. Now the hitch is movable by hand.
2005 Honda Gold Wing
2010 Dodge 3500 SRW
2013 Cedar Creek Silverback 35FL