(ET) Tiller lift, why is the bottom getting mangled?

[Christopher Zach <cz alembic crystel com>]

Quick question: When I looked at the bottom of the lift I saw that the 
lower guard had been bent over where the belt comes out. When I 
straightened it and put it on the tractor I noticed that the reason was 
that the U loop was banging into it when the tiller came up to max 
height (and started riding up vertically on the U loop)

Why is this? Am I doing something wrong?

C