The shaft on my Ace350 was too long for my 7 year old. So I made him a straight shaft out of pvc. The control box and stem/handle can be removed if needed. He gave it thumbs up.
no wobble. probably if it was longer there would be some wobble. i did make the shaft all one long piece for that reason. instead of piecing the shaft together at the tee, i cut the tee in half with the miter saw and just glued it onto the shaft. i left the control stem unglued so we can take it off if we need to.