Misalignment of stator can cause havoc as you demonstrated, also same thing when the bearings on the armature go bad. The noise was probably armature rubbing inside stator. By the way, I had a shorted armature in my drill the other day. It looked perfect to naked eye and multimeter reading also didn't indicate any fault. That why they use Growler to test armatures. I made one myself using a microwave transformer, it's pretty easy to make, and it showed that my drill's armature was faulty.
Brilliant G. [ Chartered Engineer ] Bracknell UK
Thankyou
Misalignment of stator can cause havoc as you demonstrated, also same thing when the bearings on the armature go bad. The noise was probably armature rubbing inside stator. By the way, I had a shorted armature in my drill the other day. It looked perfect to naked eye and multimeter reading also didn't indicate any fault. That why they use Growler to test armatures. I made one myself using a microwave transformer, it's pretty easy to make, and it showed that my drill's armature was faulty.
Thanks for commenting. I have been doing battle with a faulty aramture recently so I know what you mean.