My window rocks side to side what could the problem be?

A quick learner from USA says:
I have a window that rocks side to side, I was wondering what the problem could be and if it's a hardware issue, I've included a photo of my window, notice the slight gap on left side, if I rock it back the other way then the right is loose, any help is appreciated, thank you very much!
User submitted a photo of window hardware.
Profile picture of Paul
Paul from SWISCO responded:
Hello again! Always good to hear from you. I will try my best to narrow down what the problem might be. Let's do a little detective work.

Besides the rocking, does your sash open without falling down? If so, you might have too much play between the sash and master frame; specifically, there might be a bow in the middle of the master frame, giving the gap and causing the rocking motion. The solution to this is to reset the master frame, which might be a bit of a project. Let me know if that's the case and we can work from there!
A quick learner says:
Thank you so much for the help, the sash locks on one side but is noticeably loose on the other probably because of the issue you described, I'm a newbie at windows, how would you detect a problem of bowing, and if that's the case how do you reset the master frame, with shims? Thanks again for your advice on this matter!
Profile picture of Dave Sr.
Dave Sr. from SWISCO responded:
I believe you will need to remove the main frame completely from your wood opening. If this is a replacement type window, it shouldn't be to difficult. You would remove the inside trim around the window; normally, there are only 4 screws which secure the frame to the sides of the window. You could then add some wood shims to square up the window before reinstalling the screws.

If this is a new construction type window, it might be nailed in behind the siding. That could be a real job. You might want to get a professional to do the work.
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)