I have a disc very similar to that one. Same/similar thing happened to mine. On mine, the end nut and end of shaft came off, ( axle broke at end ) I lost the nut, the end plate, and a disc at that end, and I also damaged the disc on the other end because it had slack, and layed over lik ethe one in the first picture. If he has a spare axle, he can get that nut at a hardware store, and some big ( huge ) washers, and make a fix out of it. Last I checked, tsc was going to stop carrying disc parts. As for bearings.. it is a terrible setup. The bearing race is just a grooved sleeve, and the axle spacer is groved to stay in the sleeve, there is a grease fitting on the sleeve.. but it is a 'designed to fail' part in my opinion, as there is no end seals on the sleeve, etc.. dirt gets in easilly, and needs to be greased often... more than once per day.
The kind with sealed bearings hold up better.. butt he bearings are so small, that they wobble and wear easilly. These small 6' dual ganged discs ar almost a hobby setup. Anything over a couple acres needs a 11' and up.. or needs to be plowed well first....
Soundguy