1. The handlebar tiller cam is not tightened down. There should be no play in it when locking it into place. The easiest way to do this is to Release the tiller cam, give it a few more turns to the right and then clamp back into place. 

2. When there are wobbly tiller and brakes not working, that means the tiller is 180 degrees backward. It needs to be spun around and make sure the tiller folds over the knee pad and not outwards. 

These suggestions should resolve the issue with both tiller and brakes.