im familar with the cat 416s , worked for cat for yrs an 9 times outta 10 if ur having issues with the controls on the machine with the front or rear controls, it allways seemed to be the resolvers in both the primary an secondarys, if theres orings blown next to a control itll make the function next to it act up, for not more than the orings cost just go ahead an remove all of the an replacem all, just becareful an watch for the balls not to fall out, if they do just grease all the resolvers up an put the lil balls back on the end an reinstall the resolver back into valve body, the grease will help hold the ball, ITS A GOOD IDEA TO USE THE CORRECT ALLEN WRENCH ON A SOCKET AN USE A HAMMER AN TAP THE ALLEN SOCKET UP INTO THE RESOLVER ASSEMBLY, they are bad about sticking an easy to strip out the allen head screws. very easy task to do just pay attention while doing it. cat uses the resolver assemblies in several differ kinds of cat tractors an generaly when a tractor gets some age on it they tend to start to fail. they'll be missing from resolver or blown out, don't worry bout missing orings, ur filter will catchem.