It almost sounds like what my shifter was doing last year. I'd hit it, and **nothing**. It literally was gunked up. This was during the cindy training rides last year, which met at a bike shop. I asked one of the bike techs to take a look. He flipped it a couple times, then proceeded to shoot WD40 into the shifter, spin the wheels, and shift like mad. He wiped off all the mess, and the shifter has been fine ever since.