Michelle,
I just had the same problem with my shifters. I opened up the shifter box, cut two u shaped shims from 26 ga. sheet metal. I pushed the bottom shifter up and slipped one shim between the shifter and the box wall. I did the same at the upper shifter and that fixed it.You need to pack it with new grease. It may be a tempory fix as I haven't put very many miles on it yet.
Jim Carter has shifter boxes for about $45. I think I'll order one for when the shims ware our or slip out of place.
Good luck,
