My bike has almost 63,000 and I noticed the shifter getting clunky this spring. Dont know if this is the issue with yours or not and couldnt hurt to try. I wound up lubing both heim joints on the shifter linkage. I found after all of the rain and dust and just general riding just took its toll over time. The lube made a big difference in mine.
I can try that lubing thing ....
just one thing can you tell more where i do have to lube ? please