also the bike has differthe bike has never been apart. but what inside the case keeping the 1st gear in place? maybe shifting forks could be going out?
it does have a 2 to1 exhaust. ill post a video of the issue to better explain the problemBad gearboxes in these is uncommon. Some need an extra hard 1 - 2 change to prevent popping out of second. I give a rev on the change.