PS Thirty flywheel clutch

Hello everyone, I'm no expert on the thirty tractor, so I thought I would ask your opinions.
My Thirty clutch has worked perfectly since I got it a little over a year ago. The seat is wide enough for my grandson, so it gets fired up & operated ( mostly) weekly. I like to park it in front of my trailer hitch to slow down potential thieves and it starts so easily that no problems were anticipated. Little over a week ago I went to move it because the trailer wanted to bring an engine home. The engine started with a few pulls, but I couldn't get the transmission shaft to stop turning and into gear. It had been very cold ( for SC) the night before & I reasoned it must be ice somehow. An afternoon or two later I tried it & same problem. Today, I tied both steering levers back and cranked it in 1st gear. It took a minute or so of riding the brakes to the point of stalling before it broke free. I think the frictions might have been stuck to the plate, or is it possible the disc roller bearing is bad? I never knowing leave the clutch engaged overnight, but don't remember specifically that I didn't that one time. I looked in the parts book, operators book, repair book, and didn't see any way to lube the disc roller bearing. It now works as well as it ever did.
Thanks for your ideas