Strange noise

[jeffreyclay]

Hi all. I just picked up a cream-puff of a Quickie Rhapsody to replace my battle worn Pride 300. My new batteries arrived last week and I've noticed an odd noise when riding. I'll include an audio sample later but thought the conditions were odd enough to jog someone's memory. First off, it's a single frequency and the pitch doesn't vary with speed or degree of throttle. It would best be discribed as a howl or resonance. As the chair speed increases it does seem to get louder. Any ideas? Could the previous owner's ghost be chasing me?

[Burgerman]

Actually being armed markedly increases your likelyhood of being shot. Both by accident, on purpose as you present a threat, or with your own gun. Theres plenty of stats to show that. And ghosts and spirits dont exist. But ignoring all that, I have no idea! Howling?

If it was motor or gearbox related you would expect the frequency to change with speed. So no clue. If it was a really high frequency like a dog whistle then it can be the frequency of the Pulsewidth signal feeding the motor as this is constant frequency but its up at about 18K. So you woudnt likely hear it if above about 20 year old. Although my old dog could.

Is the tyre catching a plastic panel, which is vibrating at constant frequency, or a cable? Jack the wheels off he deck and run it and look carefully.

[jeffreyclay]

Here's a sample of the noise. It sounds like galling metal! The casters spin freely so I don't think it's them so I'll need to elevate the drive wheels and give them a listen. A bearing on the drive axle I can replace, what type of grease do they use in the gearbox?
https://www.dropbox.com/s/rddy8t5bn8t27y2/howler.mp3?dl=0

[Burgerman]

My GUESS is either brake seized on, or a motor magnet has come unglued and broken and is rubbing the outer armature. Or a bearing on the motor has failed and is partially siezed. All could be wrong.