Good diy'er type of job to replace which it sounds like yours needs. Did you watch it while it was running/smoking to ascertain where the smoke was originating? Sounds to me like you have a bearing gone bad. This type of stuff happens and it is usually based on mileage. How many miles are on the car? Keep in mind that if someone were to install a new belt and it was too tight then it will cause premature bearing failure.

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Jim