Something definately is bent or clogging the gears. forcing it could cause more damage if it's something inside the tranny. I heard it from someone that the lower end husqvanas had bad gear trannys, and I'm pretty sure Husqvana makes poulans and craftsmans now.
I would suggest looking on poulans site for a transmition diagram, and if you can't find it there you may be able to find something on craftsmans website.