fusers usually go in pretty easy.
usually they just slide in. sometimes they have to be shifted a little bit one direction or another after they slide to snap into place. and screw down and there is one cable that gets attached.
is there something else in the way maybe that would be crinkling the paper? usually a fuser unit itself wont do that. when they go bad they just smudge the toner. but something small can be stuck either on the fuser or in front of it and that might be what is causing both problems.
there is a locking lever that has to lock it in place once the new one is in
and there is a small electrical connection on the bottom left that may have to be attached before the fuser goes into the machine
i found another post that says there are some alignment marks that you have to make sure are aligned
you might try changing or at least pulling in and out the transfer unit as well on that page
i am going off line now so i will opt out in case somebody else can help you.
if the last thing i found does work i hope that you will still give me a good rating