Originally Posted by
FBinNY
Start with the easier approach, and flush the lever unit with WD-40 or similar, allow to dry overnight or blow dry with a hair drier, then re-lube with a light oil.
Yep, a lot of time dirt and oil gets gunked up in the shifter mechanism, causing the pauls to get stuck and not engage properly. Like FBinNY suggested, use a light degreaser and go to town on the shifter. Completely saturate it, and then let it sit for a while. Let dry, and re-lubricate with a spray oil.