Do you have a pair of trigger shifters that won't "catch" when you try to shift? The factory uses a light grease on the "arm" shown in the picture. The grease keeps everything going smooth but after a while it can dry out and get gummy. This causes the arm to either stick in the "open" position or it will move very slowly.
Both of these thing will cause the shifter to not "catch" because the arm is what holds the rest of the shifter pieces in gear when you let go of the shifter.
Simply spray some heavy duty degreaser on the arm,and move it back and forth using a small item such as a screwdriver or ice pick. It should work loose in a minute or so and work fine. After you have completely rid the arm of grease,use a silicone lubricant,or a light oil such as 3 in 1 to lubricate it to prolong life and help it from sticking in the future.
If you do all of this and it still won't catch,then your shifter is toast. Buy a new one.
