Short background: we have a single-hung window in our living room that opens sideways, and it is noticeably hard to open. I noticed recently that the lock side of the moving sash's frame seems to have been bent away from the pane of glass, probably by someone attempting to open the window by pulling on that side instead of the side closest to the frame. The window still locks when closed, but the sash doesn't have to be forced into place to get the lock to line up, so the gap remains even when the window is closed and locked, introducing drafts.
Obviously this is something that needs to be fixed, so my not-incredibly-efficient HVAC system doesn't have to work any harder than it needs to. The question is, is this a DIY-able job? I've never taken a sash out of a window before, much less disassembled a sash (as I presume I'd need to do to straighten the bent portion). Obviously if I break the window that's an expensive call to a glazier; it's a pretty big window especially for being a single pane. But, if it's possible to get the window apart easily, I should be able to get the glass out and set it aside while I pound the sash frame back into shape.
There's also the question of how the window can be closed and locked without this gap causing a problem due to the change in dimension. I'm concerned that if I straighten the sash, when I put it back in I'll simply be moving the gap over to the other side of the sash, because the window won't fully seat in the closed position in order to lock it. That could be as simple as the window's weatherproofing has degraded and I need to replace it while I'm at it, but it could also open up a whole new can of worms with regard to this window's installation, which I wouldn't have the time, money or knowledge to fix properly.
Pics when I can upload them (I'm currently at work).
EDIT:
Just to update everyone on the status of this, I was able to remove the sash from the window frame and take it apart to look. The problem turned out to be that someone else had done this before me, possibly to replace the pane, and when putting the sash back together had not properly seated the gasket that goes between the pane and sash. The gasket had been forced back into the sash frame along a part of this edge of the sash, and that in turn created pressure forcing the frame away from the pane. Removing this edge of the sash, properly seating the gasket on the pane and then putting the sash frame piece back on made everything line up again, and of course, no more gap anywhere; turns out the slot the locking tab had been fitting into was not designed for it, so with the sash squared again the locking tab fit into the groove it was supposed to. Still a bit sticky when opening it, but in a 30-year-old house some of this is to be expected, and it's much better than it had been.
Best Answer
Is it DIYable? Yes. No. Maybe?
You may find that you start the job, everything works out just right, and you complete the work in record time and under budget. More likely, you'll run into a bunch of unforeseen problems, take 5 times as long as you'd expect, and end up way over budget.
The best way to tackle DIY work that you are not sure about, is to have the resources available to quickly fix mistakes. In your situation, it might be a good idea to purchase a replacement window before you begin. If you damage the old window beyond repair, you'll simply have to install the new one. On the other hand, if the repair works out, you can return the new window you purchased.
It also never hurts to have somebody with knowledge in the type of work you're doing, so if you run into trouble they can offer guidance.
If you come across something you are really not comfortable with, there are always professionals available to do the work for you. You might also be surprised that they charge less than you might think (not always the case, but does happen).