Observe without forcing
Note whether the handle is stuck, movement is limited or there is visible damage from a safe position. Do not force controls, dismantle parts or light a fire to test an uncertain venting arrangement.
Assess the whole arrangement
Ask the provider to identify the installed damper and evaluate its condition and compatibility. A replacement choice should account for the actual fireplace and chimney, not simply the least expensive part available.
Related work
Clarify whether corrosion, masonry damage or water-entry problems require separate attention. Replacing the moving component may not resolve the condition that damaged it.
Before approval
Ask for the repair-versus-replacement reasoning, operating instructions and any limitations the homeowner needs to understand before using the fireplace again.