Thanks for all the quick responses.
Everything is new, battery, solenoid, wiring, bat. cables, resistor, key switch, starter switch and all the gauges. (The tractor was a real mess.)
So yesterday it worked fine, hit the starter button and it turned over, when I released the button it stopped. Then today, augh! I wanted to pull my hair out.
I just went out to the shed and tried to reconnect the neg. cable to the battery, to see what would happen. Whoa, a big arc snapped at me, so I guess you were right about the solenoid being stuck. So I looked at the package the solenoid came in. See the attached image.
So I dug through my box of extra parts I have accumulated and found a good old U.S.A. made solenoid so I will put that on tomorrow and let you guys know it turns out.