I have a long-term problem I would like to solve. The problem is that the drawers, especially the bottom drawer, does not properly slide in and out. It has some drag, or resistance, which gets worse as the drawer approaches the closed position. The metal tracks on which the drawer slides out and in are not spaced evenly. The spacing is OK near the front of the cabinet but that spacing becomes about 1/8" to 3/16" narrower toward the back of the cabinet. This causes resistance as the drawer is pushed inward.

Due to the way the cabinet drawer hardware is installed, I can't loosen the brackets at the back of the cabinet to adjust the width between the drawer tracks. So, I'm wondering whether I could bend the tracks near the back, going back beyond the end of the drawer's travel span. I've attached a photo to help you visualize the cabinet design.

 

Can't really tell from the photo that far away how the bracket in the back works. But I would suggest you try to spread those 2 vertical boards apart with a spacer (1x2 or 1x4) that is cut 1/8" longer than the space is wide, and force those 2 vertical boards apart, and leave it in there to hold them apart.

 

I'm not sure what you mean by "2 vertical boards". I guess you're referring to the 2 vertical supports at back that support the 2 horizontal tracks (one track on each side). The 2 vertical supports at back are metal, not wood. I've attached a close-up photo of the right back corner. As you can see, that vertical support bracket goes down below the bottom panel of the cabinet. So, for all practical purposes, I believe I can't detach the bottom end of it.

 

Force the 2 vertical tracks apart. So they aren't wood. You should surely be able to force them apart 1/8" if that is all you need. Cut a board 1/8" longer than the space between them and force it in there. Insert it in the middle and then drive it down to the bottom with a hammer.