[wingnut60]

For the drawers--remove them, probably best to get all in the same stack out at same time--get a small mag level and set on the slides to check level. Then measure width of slides using same point at front and rear. It will be the rear that is off-square--you are stuck with the front width. Sometimes, tho, a washer for a spacer may be needed at the front end one side to get the width right--hopefully, they didn't mess that part up.
At least this is how I approached it.
Joe