Papa Jo
I removed and replaced one of the pumps. It is a basic function and you should have absolutely no issue with the project. I would not try to rebuild the pump because it is a very important part that operates under pressure and heat long term. Mine had cracked in the housing. Prepare to catch the anti-freeze in some type of container for environmental reasons ...but the spill should be very small, if at all. After you study the issues, they will be very obvious..... takes about an hour to exchange if that long once you get started...
Pres