Sun beam oster center mixer arm main gear replacement

I broke the plastic main mixer gear in my Oster Mixer center. I have ordered the new part but can seem to install it correctly. Help

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0