That could be a mechanical part that is damaged and is grinding against something. Replacement Wii disc drives were pretty cheap last time I checked, but Wiis themselves are also dirt cheap, so it might not be worth replacing it. You can open it up and have a look at the mechanism and try inserting a disc while the drive is partially opened and see if you see any mechanical parts that are obviously not acting the way they should. It should be possible to 3D print a replacement part or get someone to 3D print one or even pay an online service to 3D print a part but to do that you would need a blueprint for the 3D print so it's not easy.