a collimation problem and focal length

[aerohound73]

Hello,just tried to collimate with laser my secondhand Helios 200mm F5 Explorer reflector and have a problem. It fell off my mount and dented the side.Took it apart to hammer out dent and clean the mirrors.My focusor was out of square so I fixed that also.Tried it out with star test and still not collimated(just ordered a Cheshire collimator to do the job correctly).But here is my problem: It seems my focal length has changed somehow? Before disassembling my scope all my eyepieces worked in the focusor no problem.Now...none of the eyepieces(1.25'') come into focus and my focusor travel maxs out.All it need is another inch of travel for it to work.What is going on?Any suggestions?Just a note..my scope was designed for 2 inch eyepieces and came with an extenstion for the 2 inch eyepieces.I just removed the extension and my 1.25 inch EPs work.

[Cornelius Varley]

Your focal length couldn't change, this is governed by the curvature of the primary mirror. Was has probably happened is that the primary is sitting higher in the mirror cell, you might have done this when you recollimated the telescope, If the primary is now closer to the secondary the focuser will have to be wound out farther to accommodate this.

[aerohound73]

That kinda makes sense as I loosened off the screws and then screwed them back in till I felt some pressure and left them as is.I will screw them down abit more and then try to collimate the scope.Thanks.