In the pic above, bolts marked 20 will be visible with just the rocker cover removed. On all of my DOHCs they never had the bolt 20 which goes through the top centre chain guide (item 10), the guide was just clipped on. Bolts 19 & 21 will only be visible by removing the lower timing case cover (necessitating removal of the crank pulley which will need a new stretch bolt when re-fitting). If yours is from the top of the right hand chain guide, you will need to remove the upper timing case cover to replace it.

Hope this helps.