I'm not able to check out a "part" from the vault, if i have opened an "assembly" what referencing that "part".
What is wrong about the setting?
Don't you get a warning like the attached when you try and check out an already open file? If you uncheck that box, then I believe it will let you check out the file, overwriting the open copy. If you want to keep your open copy, then instead of checking out the part, Take Ownership in the PDM Task Pane.
Welcome to the forum.
Do you have permissions to the folder the part is inside of the vault?
Just because you can open the assembly and check that out doesn't mean that the part comes along as well.
When you get the checkout screen see what permissions you have to his part file.
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