Product review (1 stars): DO NOT BUY!!! COMPLETE JUNK!!!
As others have stated, the metal inserts are not pressed in firm to the nylon and pop out. I was able to pop it with my finger! When you slide the the part onto the shaft, the metal releases from the nylon allowing the nylon part to extend further into the pump area. When this happens, the three "teeth" end up being too short to engage the rubber ring. I, as others have stated, had to use the all nylon part from the old piece for the inside so it could line up. DO NOT WASTE YOUR TIME OR SANITY WITH THE METAL VERSION, BUY THE ORIGINAL NYLON VERSION THAT HAS LASTED THIS LONG!!!!!