Driving my Fl250 around in the snow and mud and am having some low end torque issues. When I get into some crusty snow it will not downshift. Just goes slower until I come to a stop. I can review the Engine but it won’t move. I notice that the belt has not shifted back up on the driven pulley it is still down at tue high speed position. I can rock the Fl250 back and forth and eventually the belt will pop back up to its starting position. Then I can jump back in and it will go again with the low end torque. Why wouldn’t the CVT automatically down shift? Why is it sticking? This is a new machine to me. Belt seems to be in decent condition.

Welcome.
The site is very very slow now a days so it might takes days to get an answer.
Your clutches need to be serviced.
The shivs slide on the shaft and it needs to be lubed with comet lube or silicone spray.
I bet my rent money this has not been done since the machine was made.
CO