Lexmark c720 jams

I have a Lexmark C720 color laser. It works great, other than the
fact that if you print a job of about 20 or more pages, it prints that
job fine, but the next job the paper will jam in the back. We're
using good quality paper, I've changed rollers, fuser, etc., and I
really think it could heat related, because the thing gets really hot.

Any thoughts here??

thanks
Randy