What does the visible pattern suggest?

Observe from a safe position without moving the furniture. Note whether the whole cabinet appears tilted, whether gaps vary around several openings, or whether one door alone sits low. These are useful clues for an assembler, not a reliable diagnosis from a photograph.

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Start with the floor and base support

A bookcase partly resting on a rug can sit differently from one fully supported on the same surface. Sloping boards, uneven flooring or incorrectly fitted feet can also affect its position. A cabinet may therefore look tilted even when its individual panels appear correctly joined.

Record the floor type and whether the problem began immediately after assembly or after the furniture was moved. Do not crawl beneath an unstable unit or improvise a stack of packing pieces. Any levelling method must suit the product and provide the support its instructions require.

A skirting board can also prevent a unit sitting close to the wall. The resulting gap is not, by itself, evidence of a lean. Do not force the cabinet against the wall or tighten restraints to pull a distorted frame into position.

Check the assembly of the frame and back

The cabinet body needs to be assembled in the correct sequence with the specified components. Incorrectly seated joints, misplaced panels or an omitted fixing can leave the opening out of square. The doors then appear uneven because the frame around them is uneven.

On designs where the back panel helps keep the body square, incorrect positioning or fastening can affect the completed shape. Back-panel construction varies, so an assembler should compare the actual unit with its own manual rather than assume every bookcase uses the same fixing method.

Explain whether any parts were left over, substituted or forced during assembly. Keep the instructions and unused fittings available. Avoid adding screws, drilling new holes or repeatedly tightening cam fittings in an attempt to straighten the furniture; damage may make replacement parts necessary.

Distinguish hinge adjustment from damage

If the body is correctly assembled and supported, the doors may need model-specific hinge adjustment. IKEA's BILLY buying guide, for example, describes horizontal and vertical adjustment for OXBERG hinges. That is a product example, not a universal screw-turning sequence for other cabinets.

A door that sits low can also have a loose mounting plate, incorrect mounting position, incompatible hinge or damaged panel. Look only at accessible areas where this can be done safely. Do not loosen a door's fixings without suitable support, particularly with heavy or glass doors.

Crushed board, expanding cracks or a screw that no longer holds are reasons to stop adjustment. More force does not restore the missing material. Photograph accessible damage and contact the supplier or an appropriate repair professional about assessment and replacement options.

Resolve construction issues and complete required anchoring

Correct assembly, suitable floor support and anti-tip restraint serve different purposes. Follow the manufacturer's anchoring requirements even if the furniture looks straight. IKEA's BILLY guidance requires wall attachment and suitable fixings for the wall material; this should not be treated as optional decoration.

Do not detach an existing restraint to investigate a lean yourself. An assessor needs to consider the furniture, its condition, the wall and the specified fixing arrangement together. In rented accommodation, arrange any necessary permission with the landlord or property manager while keeping unsafe furniture out of use.

For help with bookcase assembly, send the product name, manual, overall photographs and accessible close-ups. Include when the problem appeared, the flooring, whether doors or shelves were added later and what anchoring is already present. Do not move the unit just to obtain a rear photograph.

“This new bookcase leans and its doors have uneven gaps. Please assess the floor support, frame, back panel and fittings against the product instructions, and advise on any damaged parts and the required wall restraint.”