I am so glad that your problem was resolved; I've had my 425 for several months (about 65 hours operating time) with no problems, but, like any machine, there will be some.
I agree that PT's manual and lack of labor on warranty is not good at all, but the simplicity of the machine and sturdy construction will probably make long term use and maintenance cheaper and easier.
Was changing the pump difficult? Even though the setup of components is not complex, it appears that a LOT of disassembly would be needed to do the work you did.
Sorry you had this problem.
Do you know if PT manufactures their own pumps? Or is it a 'standard' one?
Mark H.