Where did you get the new sender?
You said you have 45 psi oil pressure when running?
the sender is a simple switch, [not a variable resister like it would be with a gauge,] which should be dead short with that much engine oil pressure and dead open with no oil pressure. Your 'new' sender tests as -bad-, in my book.
get the right PN sender from your local Hyster forklift dealer, and give it another go.