Office chair leans or tilts to one side

What's actually wrong

Either the tilt mechanism under the seat has worn/bent, the seat plate is cracked, or (most overlooked) a caster or its socket is damaged, dropping one corner.

Symptoms

• Visible lean when sitting
• Rocking or clunking when shifting weight
• One corner sits lower

The fix, step by step

1. Sit and press down at different points of the seat to feel where the tilt originates (mechanism vs. one corner) — then flip the chair for a visual check
2. Inspect each caster and its stem: cracks, flat spots, or a bent stem that no longer seats fully in the base socket will drop one corner
3. Tighten every bolt on the mechanism first — loose bolts are frequently the actual culprit
4. Inspect the seat plate (the metal plate the seat bolts to) for cracks or bent edges; worn tilt mechanisms and bent plates are replaceable on most chair classes
5. If the chair was recently assembled, re-check backrest bolt-up and cylinder seating — assembly error mimics broken parts

When to skip DIY

A cracked weld or a proprietary mechanism on a premium chair — warranty or a furniture repair service.