I decided to try to install a cross brace inside the cabinet to spread the walls enough so the drawers would fit.
I made a trip to the hardware store and picked up:
- A 1x6 pine board
- Angle brackets with screws
- measured the front opening of the cabinet.
- cut a piece off the pine board 2mm longer than the cabinet is wide.
- used a rubber mallet to tap the board into place as a cross brace just underneath the top drawer.
- tested the drawers to make sure they opened and closed with the cross brace in place
- permanently attached the cross brace with the angle brackets.
It works perfectly. I was prepared to add a second cross brace underneath the middle drawer, but all the drawers are working well without it.
Here is a picture of the repair with a red circle around the board that I added.