Thanks a lot for your friendly comments!!
I know this belongs to the tech forums but I guess Mountain Man was right. I opened the top cover of the trans and checked the shifter forks. The one for the 2nd and 3rd gear is pretty worn and there's a lot of play. Thanks for the hint!
Seems that I've come to the right place and I did not even leave the welcome forum yet.
"Eurobolter" George
