To get the cover off you will have to remove the crank bolt and pulley. So you will need a new gasket and a new bolt just to check it, so you might aswell buy the whole kit and just do it! My Astra 2003 with 37,000 miles had the revised kit on it with the big nozzle oil jet but the chain still started to sound pretty noisey and when we stripped it out we found the guides a little worn, a couple of not very tight screws, and the bottom sproket had lost half its rubber layer! :-O so weather its a recall model aswell I'm gonna recomend that you chage it every 40,000 miles anyway.