Oh, I forgot to add, I used a commutator stone
The pic of the commutator is after I have tried and tried to get the patina to wear evenly with the stone, and also to address the brush arc (one brush has an arc but the other doesn't have one that's noticeable).
On the brush with a visible arc, it isn't bad on the nozzle (low) speed, but on hose (high) speed, it is pretty apparent. On high, the arc seems to go from side to side under that brush, almost like how the exposure lamp zips back and forth on a photocopier.
I've run the stone through both speeds, using my shop vac and air compressor in between. I did manage to knock out the periodic orange sparking but that one brush is still arcing while the other is barely perceptible. You might be right, though, it probably needs some time to wear, but every commutator I've seen has some arcing at both brushes.
Realistically, I will probably never use the hose mode, let alone find an original Kirby D50 hose in pristine condition for a decent price, but I want to make this run indefinitely and rule out any potential problem zs I think it would be pretty cool to pass this on in perfect working order to someone who will appreciate it (probably a museum) after I pass away (should have a good 55+ years in me -- I hope -- lol). I'm just thinking ahead because I believe that Kirby vacuums, especially older ones, are like heirlooms.
