What's the biggest hammer you have?
Take that hammer and shake it at the car/part, using good strong choice words, telling the car/part what you want it to do.
Set the hammer down then follow the instruction given in the posts above.
"If you don't threaten your Model A every now and then. they think you don't love them"
I use an old handle from a sledge hammer or other large handle , put it in the oil pump cut out and pop the tray out of the pan. I have done this several time and it works great.