I have been having a similar problem with my 1460. Replacing the pump didn't solve my problem. The header raise valve had a piece come apart in it. I'm still fighting header problems. The valve stack has been off 3 times, and flushed out. We keep finding little pieces getting stuck in valves. I hope it is your pump, it is an easy fix. You may also want to check the screen at the inlet of the valve stack. Good luck.