Squeaky front struts on '87 4matic

[poptest]

My car is an '87 300D Euro 4matic, and the front right strut (shocks) seems to squeak a lot when making a turn or when passing through bumps.

I've seen a lot of posts stating that the ball joints and/or tie rod ends could be at fault.

I've checked these, and the problem seems to be with the right front strut. Is it possible for a strut to be internally damaged? How do I check if the strut has failed?

Thanks a lot.

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Jake