Gary, with the renewal of the pump was the logic software changed as well? It's a very simple EEPROM change on these units and with the change in pump material is required to ensure the pump lasts and the minimum rpm of 60 is provided for the cast iron pumps.
Duty cycle at low idle is not determined by any of the parameters and only via the software, so my money would still be on the pump.
Sorry, but I am not in a position to share service information, only a little of my knowledge, and can only ask you to contact your dealer.
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