Originally Posted by well biked
I agree with bigbossman, a good cleaning is your best bet. Whatever you do, don't dissassemble the small parts inside the shifter pod....
All you need to do is to be able to observe the pawl, pawl spring, and serrated teeth that they interact with. The pawl is spring loaded, and naturally rests in the serrated teeth to keep the gear under tension. What usually happens is that the spring gets gunked up, and cannot exert enough force to return the pawl into the notches.
Just take off the cover, locate the little pawl, work the mechanism and observe. You will be able to determine in short order if this is the case with your shifter. If the pawl is not resting securely in one of the notches, you need to clean it.
"Love is not the dying moan of a distant violin, itís the triumphant twang of a bedspring."
S. J. Perelman