collimation screws issue

[john willis]

hi i recently contacted this forum with problems setting up my 10 inch skywatcher classic dob. telescope.luckily i found a local astronomer who helped me with it.i still have a problem however with the collimation screws on the primary mirror.i think because the tube had been damaged and is still not perfectly round,one of the studs on the mirror is fouling on the side of the hole,and the knurled end just unscrews without moving the mirror.so effectively i only have 2 screws to collimate.the only fix i can see is to drill the holes slightly larger and put thin washers on the spring side{i already have them on the outside}to stop the springs fouling in the bigger holes.has anyone come across this problem and would you agree with me,i would really appreciate advice before going ahead.

 

            thanks,john willis