Nut comes off, hits idler pulley

[Robbie100]

The rower at the gym was making a funny noise at the start of a workout and was quiet again soon after. A few days later a nut was found beneath the rower. It turned out the nut (no. 18 on parts list) that locks unto the buttonhead screw which secures the end cap has come off. Checking for damage inside reveals the nut somehow imbedded itself between the chain and the chain idler pulley. The pulley appeared to be okay but you can see a dent where the nut was forced into. The nut must have been slowly loosening itself due to the vibration and flew off to the pulley section when the rower was moved during the gym clean up at the weekend. Otherwise it would just land on the plastic cover. Design consideration for Concept 2 - change to nylock nut, or just spot weld nut to end cap hook?

[Carl Watts]

It should be spot welded to the hook. The problem is it just spins as the bend is not close enough to the nut to stop it turning. Had a real issue in getting the cap off once as the nut just kept spinning. Not a great design in this area.

[icomefrombirmingham]

The spot weld idea is excellent.
I had my model D appart at the weekend and geting the end cap back on was a bit of a fiddle. You have to hold the hook and nut inside the frame with stretched fingers while trying to locate the bolt/screw into the nut from the outside. Dropped the nut several times.
Welding would be the solution.