Motor armature free to drop down at least an inch too low.

[AlexM]

Good chance what ever held it up has mented or broken off
Usually it is nothing more than a boss cast into the end cover .
There is not much axial load on the rotor when the motor is running as the magnetic fields will tend to centralize the armature inside the field windings / magnets
What pulls the armature down is the action on the blades which trys to suck the air ( and grass) up so of course pulls down with equal force .

Thank you, bertsmobile1. From what you wrote, the melted things I've been calling "tabs" are "bosses" that protruded from a ring that goes around the top of the armature (or should I call it a rotor?). What did those bosses attach to in order to hold the armature/rotor up? I expect they attached to the white plastic, but I can't tell how. What you're saying about the forces that act on the rotor makes perfect sense, but since I first started looking at this, it has seemed strange that those two little pieces of metal were responsible for holding the armature/rotor up.

 

[AlexM]

In case anyone wants to know how this turned out, I felt pretty stupid once I saw the bottom of the housing in a better light. As StarTech noticed just from my photo, it had failed, but it had looked to me as if nothing recent had happened to it (no fresh breaks, etc.) until I got a better look and saw fresh metal where it had, in fact, just broken on all four of the sheet-metal bridges that held the armature up. It made much more sense to me that those bridges held the armature up than anything on the top alone, but someone had told me it was just a piece on the top, and it seems that perhaps some securing on top and bottom is necessary, because my attempt to fix it didn't work at all. I ground the paint away and tried JB Weld on the four bridges and ran the motor without the blade attached as a first test, but the bridges all broke at the same places right away, and the motor seemed to grind on something even though the armature didn't fall significantly. I don't know whether a real weld would fix it, but I highly doubt it, and I'm reluctantly giving up on keeping it. I'll recycle the metal or perhaps let someone have it who wants to try welding it. Does anyone know how much weight of copper is in one of these motors (for recycling)? Thank you all for your contributions and kindness not to note how stupid I was!

 

[sgkent]

that comes back as a corded lawn mower, which the motor was never available in the parts diagrams, even the owner's manual. I'd scrap it and move on. You aren't playing with batteries, you are playing with a 120V motor and plenty of amps if you screw up.

 

[AlexM]

that comes back as a corded lawn mower, which the motor was never available in the parts diagrams, even the owner's manual. I'd scrap it and move on. You aren't playing with batteries, you are playing with a 120V motor and plenty of amps if you screw up.

Thank you for looking it up. Yes, as I wrote above, I've given up on restoring it, sadly.

 

[sgkent]

Thank you for looking it up. Yes, as I wrote above, I've given up on restoring it, sadly.

Look at the bright side - at least you won't have to worry about running over the extension cord, or one of the animals chewing on it.

 

[AlexM]

Look at the bright side - at least you won't have to worry about running over the extension cord, or one of the animals chewing on it.

Thank you. The cord was a pain, especially in my complicated and too-large yard.

 

[sgkent]

Thank you. The cord was a pain, especially in my complicated and too-large yard.

I borrowed a friend's like that about 35 years ago. Having a corded hedge trimmer, or weed wacker was a pain enough, but avoiding the cord constantly with his mower made me swear I would never own one. Lots of options out there these days.