Hi, I am a professional certified mechanic, with an engineering background, and 35+ years experience. I will do my best to assist you. Also keep in mind I don't know if you are a pro or a novice so we may have to fine tune the answer. Feel free to add any additional info you feel is needed as we go on. Always keep in mind that I am here to help you with any questions.

If the actual blower motor is just about worn out, it can have what is known as endplay. That is where the motor shaft can be pushed in, and out a bit because of wear. On an incline the endplay can switch to one side or another, and slow the motor down, because of friction. Normally if this is the problem the blower motor wont be quiet, and it will have a few strange sounds. That is the only thing I have ever seen slow a blower motor down. If you have any more questions, as always, I am here to help. Good luck with it, have a great day, and Thanks for using Just Answer.

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