I don't agree that cutting these is a good idea. They're tall, and they may have hardware in critical locations that would disallow modification. Also, cutting coated surfaces like that often leaves a ragged edge.

I would shim out the mounts to a single plane. Set the mounts at each end and run a line between. Install spacers to bring everything out as needed.

Seeing the mounts I'd offer these tips:

• The shelves that are on sliding poles can simply be moved out as needed. Use felt pads or other appropriate spacers behind to keep them in position.
• The shelves that have keyhole retainers are little more fussy. They'll need full-height, rigid spacers behind to support weight. I'd cut some strips of pine board to the correct thickness or stack strips of cardboard and glue or nail them along the vertical rails at each end of the back panel. One in the center wouldn't hurt, either.
• Now you can either extend the wall screws a bit as needed (maintaining adequate penetration into wall framing), or shim out the keyhole plates a bit with washers or whatever. Again, maintain adequate screw penetration by using longer screws if necessary.
• Consider connecting the shelves for even more stability. Use double-sided foam tape squares between each section at the front and rear. Waxed paper against the adhesive should allow you to position the shelves before pressing things together.

I don't agree that cutting these is a good idea. They're tall, and they may have hardware in critical locations that would disallow simple modification. Also, cutting coated surfaces like that often leaves a ragged edge.

I would shim out the mounts to a single plane. Set the mounts at each end and run a line between. Install spacers to bring everything out as needed.

Seeing the mounts I'd offer these tips:

• The shelves that are on sliding poles can simply be moved out as needed. Use felt pads or other appropriate spacers behind to keep them in position.
• The shelves that have keyhole retainers are little more fussy. They'll need full-height, rigid spacers behind to support weight. I'd cut some strips of pine board to the correct thickness or stack strips of cardboard and glue or nail them along the vertical rails at each end of the back panel. One in the center wouldn't hurt, either.
• Now you can either extend the wall screws a bit as needed (maintaining adequate penetration into wall framing), or shim out the keyhole plates a bit with washers or whatever. Again, maintain adequate screw penetration by using longer screws if necessary.
• Consider connecting the shelves for even more stability. Use double-sided foam tape squares between each section at the front and rear. Waxed paper against the adhesive should allow you to position the shelves before pressing things together.

I don't agree that cutting these is a good idea. They're tall, and they may have hardware in critical locations that would disallow modification. Also, cutting coated surfaces like that often leaves a ragged edge.

I would shim out the mounts to a single plane. Set the mounts at each end and run a line between. Install spacers to bring everything out as needed.

Tell us more about the mounting system for more specific advice.

I don't agree that cutting these is a good idea. They're tall, and they may have hardware in critical locations that would disallow modification. Also, cutting coated surfaces like that often leaves a ragged edge.

I would shim out the mounts to a single plane. Set the mounts at each end and run a line between. Install spacers to bring everything out as needed.

Seeing the mounts I'd offer these tips:

• The shelves that are on sliding poles can simply be moved out as needed. Use felt pads or other appropriate spacers behind to keep them in position.
• The shelves that have keyhole retainers are little more fussy. They'll need full-height, rigid spacers behind to support weight. I'd cut some strips of pine board to the correct thickness or stack strips of cardboard and glue or nail them along the vertical rails at each end of the back panel. One in the center wouldn't hurt, either.
• Now you can either extend the wall screws a bit as needed (maintaining adequate penetration into wall framing), or shim out the keyhole plates a bit with washers or whatever. Again, maintain adequate screw penetration by using longer screws if necessary.
• Consider connecting the shelves for even more stability. Use double-sided foam tape squares between each section at the front and rear. Waxed paper against the adhesive should allow you to position the shelves before pressing things together.