Hello again, i have a yaris 2005 1.3 vvti it has a small oil leak, and have a few spots on drive near front right wheel. On examining, looks like might be rocker cover, so is it easy job to do ? There is also a  6" square silver coloured box shaped thing under the pulley area , and that has oil on underside of it too, any idea what that is ? My plan is to change the rocker gasket, clean off the oily bits and see if its fixed. Only problem is i cant find a guide. any hints and