you try to install the rod as best you can in the middle of what you are cooking or at least through it were it will be reasonably balanced. this will take a bit of trial and error.
now make sure that the weight is loose. now you put it on the ring but not in the motor yet. now let it settle. the heavy part will be on the bottom. so now you put the weight straight up in the air and tighten the end piece to hold the weight in place. now see how it spins. it should rotate easily. it won't be perfect so don't try for that. moving thw weight in and out is how you fine tune it.