Why Doesn't it Work?

I pulled the lower unit from my 4hp Yamaha outboard today to rebuild the water pump. I was fortunate to find a water pump rebuild kit at a local marina. Inspecting the water pump I can't understand why it didn't work?? 3 of the 6 veins were completely broke off, 1 of the three remaining was broke in half and the other two were cracked. On top of that one of the remnants was stuck in the water passage blocking over 50% of the pathway. The guy we bought the motor from said he just rebuilt the water pump. I say BS.