I have a 250es with timing chain noise. I have the valve cover and the right side case cover off. The timing chain tensioner was fully extended but the chain was still loose. The guides and sprockets show little wear, so I presume the timing chain needs replaced, but my manual does not have a procedure to check the timing chain. How do I determine if the chain is bad, and can the timing chain can be removed without pulling the head and cylinder? Thanks.