How to test fuel sender

Well got the tank out and sender. pretty rusty. I have to assume it is so rusty that it dont work. I tried to test Ohms on the sender but not sure how to touch body of sender because it has rubber around it. unless I can just touch it anywhere else other than the stem?
Also the new sender has a wire that is wrapped around? there was no wire wrapped on the old sender.

Also I assume the older sender is trash, right?