Have you tried this https://forums.maplesaga.com/index.php?threads/the-missing-mechanical-quest-is-bugged.14537/
Can't turn it in to Dr. Kim in Omega Sector either EDIT: Does it make a difference that the item in the inventory is called Machine Parts instead of Mechanical Parts for some reason?
If you pick the ETC option (2nd option) from the NPC dialog, he will take the 10 Missing Parts from you and reward you your prize.