If the 4mm EP is the only one that you have that doesn't focus then the main mirror ususally doesn't need to be moved very far. Often it only takes adjusting the mirror cell out a bit by moving the adjusting screws a few turns to allow the mirror to move towards the secondary.
I'd also make sure that the collimation is set properly, especially the position of the secondary in the focuser tube. Test equipment is easily built from odds and ends and there's several websites that go through the construction and usage of the tools. There's no need for laser collimaters other than to do the job in seconds instead of minutes and their big usage is for those who build truss tube type scopes that need to be aligned everytime that they are setup.