rumbling noise in Black & Decker CMM 1200 cordless mower

jad11050

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  • / rumbling noise in Black & Decker CMM 1200 cordless mower
I've got a B&D CMM 1200 (2009) cordless electric mower. This season it has developed a low rumbling noise, clearly some sort of vibration that is amplified by the whole mower body. It comes and goes, unpredictably, sometimes affected by moving/turning/tilting the mower and other times just coming and going even as the mower is held still over concrete driveway. I opened it up and ran it with the body top removed; no difference. I didn't find anything loose (I had replaced the battery myself so I was concerned that something may have gotten loose) but lightly tightened the three bolts holding the motor housing on to the mower body; no difference. Running it again it looked to me as though the motor shaft seemed to wobble/oscillate slightly and even spark a tiny bit and that seemed to coincide with the noise, but it also looks like the brushes or whatever they are called seemed designed to have a little give so I don't know if some wobble is normal. I've had the mower for five years, and have had almost no problems. Last year the mower's performance suffered and it seemed a little noisier but the B&D service guys said that was due to an improperly balanced/sharpened blade; balancing the blade fixed the problem. This is a different louder noise that comes and goes, and doesn't seem to affect performance. Anyone know/suspect what is going on?
 

motoman

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  • / rumbling noise in Black & Decker CMM 1200 cordless mower
Jad, Just a long shot and to say hello. I do not have this machine, but the rumbling is classic description of bad bearings. The little balls get chipped, galled, or loose their hard surface. Your instinct to wobble the shaft may be right on. Go back and rotate the shaft again while pushing down . Sometimes you can feel the roughness. I don't know the price range but if low level you may find you cannot even get the thing apart to repair it. But if you can and it's bearings they should be cheap if available.
 

jad11050

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  • / rumbling noise in Black & Decker CMM 1200 cordless mower
Thanks, I'm a little afraid to try to replace ball bearings. It sounds like the sort of thing that would seem simple but end up being confoundingly difficult to get right. I may have to take it in for service, but that means an hour drive to drop off and another hour drive to pick up and then I'm without the mower in between. We'll see. Thanks again.
 
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