Evening again fxxxrr,
Sounds like you’re a chip off the old block!

Sounds like you’re innovation in solving the wheel problem is something your old man would be proud of! 10 points!
Now, the seat problem. I can help you with that. I’ve collected a few seats and seat springs from tractor model machines. They are pretty much identical to the one that would have been on that machine originally. My shout.
Cheers,