Ideal to give your legs the rest, not a good processing

I bought the coach to (also called LegDay neudeutsch) to give my legs tag for squats and leg presses herewith my quads and the rest - much is revealed - it works perfectly. Although it looks easy, it brings out already impoverished thighs out the rest and at the last repetition, it is difficult not to fall out of the coach.

The coach is as usual delivered in kit, all necessary screws and mounting hardware are included. Unfortunately, the build quality to be desired, because the assembled coaches stands (not least wg the base plate which her feet takes) pretty shaky on the ground, in addition to incline with frequent load (I weigh about 91kg) at the outer to bend (the quite thin plate floats quasi in the air).
Happened so far in the use of the coach not, but in the beginning I had, thanks to the non-existent stability (wobble, wobble) a very strange feeling, which has, however, laid.

The manufacturer should rectify again and implement a better fit and the approach the problem to thin base plate.