on that sled you have to loosen the two outer wheels. they are only guide wheels, not drivers, you dont really even need them on there but go ahead and keep them. be sure and mark the location although the markings on the shaft should be evident. no way to get the shaft out otherwise.
heres the butt kicker. those little set screws will be stuck. they strip easy as well. being they are like a 2.5 or 3mm allen head, if you have cheap allen wrenches you can twist them up almost as easy as stripping the set screws.
in other words, use good tools, be sure and pre-soak with kroil or pb blast, and if your up to it and careful, some stragetically place heat will help.