There is a pressure switch on the pump that needs full pressure to turn the pump off and turn the green light on. I would think that if it operated properly before you changed hoses and replaced seals that there is still air in the system and would need to be bled off to cure the problem. Be very careful if you crack a line to do this because the pump puts out over 1400 lbs pressure (per lippert rep) The guys at lippert are very helpful, I would suggest calling them and ask how to bleed the air off so you don't get hurt in the process.
George & Jerri
06 GT 340 TSSE