Kevin I totally understand it's possible but probability depends on multitude of undetermined factors (engine speed, firing order, engine accessory loads, tension of accessory and timing belts,etc . I don't think we can give sure answers to Marcus' questions. Speaking in relation to harmonic dumper.
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Do harmonic balancers ever go bad with normal wear and tear

Yes
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or would improper function of a harmonic balancer be a result of improper removal/installation?

Yes
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Hypothetically, if I were to purposely install a bad harmonic balancer on a perfectly good engine, how long would it take for the abnormal vibrations to wear out the crankshaft bearings? (1,000 miles, 5,000 miles, 10,000 miles, etc)
Mark

Depends how "lucky" you are.
I'd still would like to know what exactly was replace and how total engine health was diagnosed.
Regardless it might be really hard to pin this down on dealership performing timing belt change.

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