Bought a 1960 Cub previous owner had engine rebuilt primed pump started good oil pressure parked for a few days had to reprime pump would not pick up oil pressure had to do this every time after it was parked for a few days would the wrong pump gasket cause the pump to lose prime?
Yes, that is exactly what happens if the oil pump gasket is too thick. There are gasket businesses that simply cut the pattern for the cub oil pump but do not check into what thickness that gasket material should be.
Really sucks because the only thing you can do is split the tractor and replace it with the correct one.
If you suspect this, the correct gasket should be thin like paper.
I went through this. If I remember correctly, the pump and its gears should be about flush and the gasket is the clearance. The paper gasket was .004 and the incorrect one that some a$$ sold me was .020. The thicker and incorrect one will allow the oil to drain past the gear ends and you will have to prime it every time you use it.
Best of luck.