I am guessing its not "New" but new to you. They don't make the 250 anymore unfortunately. First thing I would do is change the trans fluid. It may have the wrong or no fluid in the trans and the temps could be causing issues with the wrong fluid. Make sure the shifter is not bent and hanging up on anything. Then I would check the shift shaft. Not sure which side the chain is on the 250 but if the change comes off and hits the shift shaft or cases, it could bend the shaft. That's where I would start.