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I think that the answer to your question depends upon, who the warranty is from.
For a warranty from Pacemaster themselves, the motor would have to be replaced by them (or their authorized dealership in your area, possibly, but also perhaps not. It depends upon their exact warranty coverage terms, and also their allowable leeway and choice or preference.)
Have you opened the Pacemaster treadmill already? if so, that may have broken seals that, broken, will prove the warranty invalidated. I hope not...