I have the same problem with the 26mm QX eyepiece. When I push it all the way in till it bottoms, then it wont reach focus. All I do though is to pull it out about 12mm , lock it in position and it works fine. All the other eyepieces - Hyperion, Plossl, Orthoscopics, work fine. I think it might be something to do with how far the primary mirror is screwed down towards the bottom of the scope. Maybe adjusting the mirror up or down and then re collimating, may work, but really it's no hassle to pull the EP out a bit. That eyepiece is GREAT - I love it
