The shaft broke on the right drive pump a few weeks ago. Parts were replaced and everything went together well. The problem now is we cannot get the pump to prime. I have called Exmark two times and done as they instructed with no success. I can get it to pick up and drive the motor for a few seconds but it always looses it and pushes the fluid back out of the tank. Does anyone have any ideas or experience priming these pumps? Any help is much appreciated.