Office chairs

How Do You Fix an Office Chair That Sinks or Rolls Badly (Gas Cylinder and Casters)?

Published · By Ergocrew · Specs and guidance as of that date, from the pages under Sources

Summary

For a chair that sinks, first ask the maker to check the height-control mechanism and identify a compatible replacement cylinder if needed. Replace the complete specified unit rather than attempting an internal repair. For poor rolling, inspect the wheels for debris or damage and confirm that the casters suit your floor. Check warranty coverage before buying parts or dismantling the chair: model fit and the cause of failure matter more than a cylinder's class label alone.

Why a chair sinks

The height lever on most office chairs works a gas lift cylinder in the center column. When the cylinder wears, it can no longer hold the seat at the height you set. Note whether the seat settles gradually or drops when loaded; that is useful information for a service request.

Record what happens when the chair sinks: whether you touched the height lever, whether it settles at a particular setting, and whether the change occurs during recline. Give that description or a short video to the maker. It helps distinguish the height-control problem from tilt movement without diagnosing a worn cylinder from the symptom alone.

Replacing a gas cylinder: what to match

A replacement has to fit two sockets: the seat mechanism above and the base below. It also has to give you a usable height range. Before ordering, compare these points with the maker's spec or with the original part:

Cylinder replacement is model-specific. Herman Miller's New Aeron instructions, for example, specify a nylon cap, lift-off tool and covered dead-blow hammer, followed by removal and refitting of the complete cylinder. They are not instructions for a Sihoo or ProtoArc chair. Obtain the correct procedure and parts for your model, or use the maker's service provider. If coverage may apply, get that decision before disassembly; afterward, reset and check the occupied seat height.

Casters, floors and rolling

OSHA's chair guidance says a chair "should have a five-leg base with casters that allow easy movement along the floor." It also asks for casters "appropriate for the type of flooring." A chair that rolled well and now drags may have hair, carpet fiber or grit wound around the axles. Pull the casters out of the base if your model allows it, clear the wheels and axles, and check each wheel for flat spots or cracks.

If the casters are clean and the chair still drags or skids, the wheels may not suit your floor, which is the mismatch OSHA's "appropriate for the type of flooring" wording points to. Replacement casters have to match the stem that fits into the base, so read the maker's spec or measure the old stem before buying. ProtoArc lists an "Alloy base; quiet-roll casters" for the EC200 Pro. A cracked leg on any base is a reason to stop using the chair until the base is replaced.

What the warranty may cover

Sihoo's US warranty policy, checked 2026-11-02, gives 3 years and covers manufacturing defects, structural failures under normal use and mechanical issues not caused by misuse or third-party alterations. It excludes normal wear and non-Sihoo parts or accessories. Ask Sihoo whether your sinking cylinder or caster fault qualifies before buying a part; coverage depends on the problem and purchase conditions, not just its age.

Sihoo's warranty policy applies to products bought directly from its official U.S. website. Purchases through authorized third-party platforms get limited coverage with valid proof of purchase. The policy is valid only for the original purchaser and is non-transferable. To claim, Sihoo asks you to email [email protected] with a description of the issue, photos or videos of the problem, your order number and your contact information. A short video of the seat sinking shows the problem more clearly than a photo.

When to replace the chair instead

For a recently delivered chair, ask about a return or replacement before starting repairs. Sihoo gives a 30-day return window from delivery, but its policy combines unused/original-packaging language with FAQ wording accepting normal use. Confirm eligibility for an assembled chair with the specific fault. Clearance and final-sale items are excluded; do not assume every new chair can be returned after use.

Outside that window, compare the cost of a cylinder and casters with the price of a new chair. Also consider whether other parts are failing at the same time, such as the recline, the armrests or the base. If you are pricing a replacement, here are four chairs at the lowest listed option at each maker's US store:

ModelPrice at the maker's US store, checked 2026-10-13Maker's listed detail (warranty, returns or part)
Sihoo M57$239.99 at Sihoo's US store30-day returns
ProtoArc EC200 Pro$249.99 at ProtoArc's US storeClass 4 (TÜV-tested) cylinder; alloy base
Sihoo B300 Pro$259.99 at Sihoo's US store3-year warranty
Sihoo Doro C300 Pro V2$429.99 at Sihoo's US store3-year warranty covering manufacturing defects

If repair costs approach the price of a replacement, compare the ProtoArc EC200 Pro at $249.99 at ProtoArc's US store, checked 2026-10-13, as one option with a stated Class 4 cylinder and alloy base. Confirm its seat fit and the availability of compatible service parts with ProtoArc. Those specifications describe the original chair; they do not make its cylinder an upgrade for another model.

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Related guides

Sources

  1. Herman Miller, New Aeron Cylinder Replacement
  2. OSHA Computer Workstations eTool, Chairs
  3. ProtoArc, EC200 Pro Ergonomic Office Chair
  4. Sihoo, B300 Pro Ergonomic Office Chair
  5. Sihoo, Doro C300 Pro V2 Ergonomic Office Chair
  6. Sihoo, M57 Ergonomic Chair
  7. Sihoo, Warranty Policy
  8. Sihoo, Returns Policy

We have not tested these products. Specs and guidance are as published on these pages on the date above and can change; the manufacturer's page for your model has the current details.

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