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So to start, a banging noise would not be a bearing issue, that would be a broken shock or inner basket support brace, or counter balance weight that had come loose. If the noise is just much louder and it's like a jet engine, that is a bearing going out and that requires new bearings and seals as well as a new shaft for the inner basket support. The shaft is sold separately from the tub, but the bearing is only sold as the entire rear outer tub which means that you'd need to order and replace the entire rear outer tub and inner shaft to resolve this issue I'm sorry to say. The part numbers are DC97-14421A for the shaft and DC97-14604D for the rear outer tub. It's about $500 in parts along so it may not be worth fixing, but that's completely up to you to decide.
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You usually won't see anything until the problem gets really bad. But that being said, I've never heard anything else cause a louder spinning noise which gets louder the faster it spins other than the bearings on a washer.