A: Grasp the wings of the needle on the left and right hand side, ease the back end of the needle body out from underneath the clip on the back of the cartridge.

This will release the needle from the cartridge.

To put the new one it, ease the back of the needle body underneath the clip on the cartridge and the front end of the cantilever will rest in the rubber boot on the front of the cartridge. Answer provided by:  Kyle (8/12/2014)