Casters not rolling / scratching the floor

What's actually wrong

Hair and debris have seized the caster bearings, or the wrong caster type is meeting the wrong floor (hard casters on hardwood, soft on thick carpet).

Symptoms

• Chair drags or judders
• Floor scratches appearing
• One wheel locked

The fix, step by step

1. Flip the chair and pull hair/debris from each caster (scissors + tweezers; it's always worse than expected)
2. Pop out stubborn casters — most are friction-fit stems that pull straight out — and clean the sockets
3. Replacing: match the stem size (7/16" x 7/8" grip-ring covers most office chairs) and buy the right wheel for your floor: soft polyurethane for hard floors, hard nylon for carpet — rollerblade-style casters are a popular hard-floor upgrade
4. Press new casters in until they click

When to skip DIY

Never.