JD 50 Water Pump problem

I've been rebuilding a JD model 50 tractor for quite some time. Got to the point to where I could add all the fluids back in and try to start it up. After putting in the 5 gallons of coolant into the radiator, I noticed the water pump was leaking out the bleed hole. I had rebuilt the pump, put in new bearing and seal, so this did not seem right. Pulled the pump out and took it apart. Noticed right away that the little plastic washer with the two tabs on it had one tab broken off. Not sure if this happened while assembling or disassembling the pump. Thought that if it broke while putting the new parts in that perhaps this was the reason for it leaking. Got a new seal kit, carefully put the water pump back together, making sure that when pressing the bearing into the impeller that the tabbed washer was correctly aligned. Put the pump back in the tractor; filled with coolant and again had a steady drip coming out the bleed hole. What am I missing here?
Took the pump apart again and the new tabbed washer is broken again. I don't see how pressing the impeller off should break that washer... is this normal? Whats the answer for fixing this leak?

The 2 tabs need to line up in the slots,,and it is near impossible to keep them in place,,that is why we tell people to buy a rebuilt one for that early model pump, the latter models have a different ceramic washer and has no tabs to line up..

Yea, I was super careful in getting those tabs to align with the slots... thought I had done it properly, but
apparently not. I'm sending off for a new pump... tired of messing with this one. Just wondered if there
was something that I was not understanding about this tricky sucker....

I once used zip ties to hold it in place and pressed it together just enough to be sure they were lined up, then removed the ties and pressed it on together..."after" I broke a couple...