What's the trick to getting the old bearing off? I can't take the part off the end of shaft by bearing.

there is no trick...
before you remove the shaft ends draw a chalk line from end to end so you do not put it back together wrong
seperate the shafts and the remove the nut at the end of shaft closest to the bearing.

the use chisel to gently knock the bearing off.

be very careful to keep the alignment