It's really a common problem with an easy answer. Take and pull the screws for the primary mirror holder to the tube and move the assembly up the tube until a 25mm EP will focus at infinity about 3/4 of the way up on the focuser. If you have a 4mm EP, set it to be just off the bottom of the adjustment. This will allow for almost (supposedly) any EP in the scope without running out of room in focusing. Putting the holes in for the primary holder is the last set of holes as a mirror focal length is only an approximation when given by most makers. This is because the final work on the mirror oftentimes changes it's distance a bit. Doing the primary mount last also makes the set you do drill to be the correct ones. Ya just gotta live and learn. Sorry you're going to have two sets of holes in your tube.