My suggestion would also be to take the housing apart. You may find the loose piece floating around in there and re-install it easily. The other option would be to check the salvage route and find a workable housing assembly to replace the defective one. Just a thouht or two since I have done way too much "Shade Tree Mechanics" to spend $400.00 for a tiny part which may be easily repaired with "sweat equity"
John