I've had the luck to buy at least three new Seal Power, maybe they where Speed Pro brand standard, maybe high volume, to many years ago to remember now, oil pumps that had the solid sided 440 bypass valve in them instead of the SB one with the holes in the sides
Let us know what you find to fix it
I drill a small hole in the cup and then a #8 sheet metal screw in that hole to pull the cup to find out if it was stuck and learned that they had the wrong valve in them from the factory