I was having some 1 inch free play on my steering wheel. I change the bottom joint (Item No.4) as advise by some people. The problem improved but the free play was still there. So in order to resolve the problem, I did the test above and find there were some free play for the joint (item 3). Even though it is small but it is magnified by the steering wheel diameter. Instead of changing item 3, I put a lot of silicon and inject it between the gap of the joint to "stiffen" it. The result is quite good. Now my steering feel stiffen and the wheel is also tracking properly. The silicon is only temporary solution. Now I know what to change in my next visit to the workshop. Note: Dont try this at home. I am not responsible for any mishap.