To get the old one off try to heat the gear, I'm assuming it is aluminum, without heating the cam. A small torch works well. To put one on get the cam as cold as you can. Put in in the freezer or leave it out side if your ghetto is a cold one. Put the gear in the oven at about 250. Make sure the retainer and key are on place. Using pot holders you should be able to pretty much drop it on. Have a mallet handy just incase you need it. This method keeps from displacing metal from the gear. Having someone to hold the cam helps or you can carefully clamp it in a vise. Hope this helps.
