High-Back Office Chair Assembly

The assembly of a high-back office chair should follow a 'bottom-up' logic, with the specific steps outlined below:

1. Prepare Tools and Inventory Parts
   After unpacking, choose a well-lit and spacious area to categorize and place all parts. The main components include a five-star base, five casters, a gas lift, a seat plate, a seat cushion, a high-back section, armrests, a screw pack, and installation tools (such as screwdrivers, Allen wrenches, rubber mallets, etc.). Be sure to verify that the number of parts matches the instruction manual to avoid missing critical components.

2. Install the Five-Star Base and Casters
   Place the five-star base face up and align the metal rods of the casters with the base holes, pressing vertically until you hear a 'click' indicating the clips are in place (for threaded casters, tighten them clockwise). After installation, gently shake the base to check if the casters are secure and avoid looseness during subsequent use.

3. Install the Gas Lift
   Insert the thicker end of the gas lift vertically into the center hole of the five-star base and press firmly until it is fully inserted at the bottom. For some models, you may need to remove the plastic protective cap at the top of the gas lift to ensure a smooth connection with the seat plate. The gas lift is the core component for adjusting seat height, so ensure it is installed vertically without tilting.

4. Secure the Seat Plate
   Flip the seat cushion so that the bottom is facing up and align the seat plate with the pre-installed screw holes. First, manually screw in all screws loosely, then gradually tighten them using the 'diagonal tightening method' (e.g., tighten the top-left screw first, then the bottom-right screw, alternating sides). This method prevents uneven stress on the seat plate, which could cause it to tilt and affect seat stability.

5. Connect the Seat to the Gas Lift
   Lift the seat with the installed seat plate and press it vertically down onto the top of the gas lift until the seat fits over the gas lift. Apply vertical force only to avoid damaging the gas lift or tilting the seat due to sideways pressure.

6. Install the High-Back and Armrests
   Insert the high-back section into the connection holes at the back of the seat (for some models, secure it with screws from the back) and ensure the clips or screws are fully engaged. Then, install the armrests on both sides of the seat using screws, paying attention to left-right symmetry, and tighten all screws to prevent looseness.

7. Install the Headrest (if applicable)
   If the chair comes with a headrest, install it in the reserved holes at the top of the backrest, tighten the screws, and adjust the angle and height to a comfortable position. The headrest supports the neck and helps relieve fatigue from prolonged sitting.

8. Adjust and Inspect
   Adjust the seat height according to your height (feet flat on the ground, thighs and calves at a 90-degree angle), armrest height and angle (arms relaxed naturally). Finally, check that all connections are secure, especially the interfaces between the gas lift and the five-star base, and the seat and the seat plate. Gently shake the seat to confirm there are no unusual noises or looseness.

Precautions:

• Before assembly, be sure to read the instruction manual for your specific model, as some designs (such as the operation method of the height adjustment lever) may vary.
• When disassembling, note that separating the gas lift from the base and the seat from the gas lift can be difficult; proceed with caution to avoid damaging components.