My Prevost dash heat circulation pump is leaking and I have replacement parts, seals, impeller, gaskets, etc. I ordered from Prevost. I have removed the pump and cannot disassemable it. Can anyone tell me how to remove the impeller to get at the seals? Prevost has an upgrade in a seamless motor/pump setup for $800 but I opted to repair mine for $100 in new parts. Now I am stumped. Any help would be appreciated. This is the pump located on the ceiling in the front center bay