(ET) Mower magnet motor maintenance

[Chris Zach <cz alembic crystel com>]

So was doing the fall mowing with the E20 and noticed that one of the 
motors was cutting out due to the breaker tripping. Great, that means 
two things:
1) Something is wrapped around the shaft
2) The magnet is broken.

So stopped the tractor, parked it, lifted the deck, and took apart the 
motor. This can be done quickly by removing the cap, removing the 2 
bolts at the base of the long screws, pulling the top off the motor and 
pushing the armature+blade down and out.

In this case the problem was clear. Magnet had come loose and adhered 
itself to the armature.

On the positive side the magnet was still in one piece. Normally it's 
broken into 3 parts, all of which never want to stick together again. 
Regardless repair is the same.

Here's a picture

https://i.imgur.com/F4lBzCZ.jpg

First: MARK THE TOP OF THE MAGNET A LOT AND TAKE PICTURES. You can't 
reinstall it upside down so before taking it off the armature you need 
to make sure you know which end is up.

Second: Remember magnet is fragile. Don't put it on the tractor, near 
metal surfaces, or anything as it will SNAP to these items and possibly 
break. Which sucks.

Third: Clean up the back of the magnet. Most of these seem to have been 
secured with two strips of stick tape on each end. Probably the most 
cheap-ass solution I have seen and it's amazing they lasted 50 years. 
But it's been 50 years and the tape/glue is going fast now. So if we 
need to do a 100 year solution.....

Anyway use your wire brush to clean up the back of the magnet and make 
it smooth. If the magnet is in parts, clean up each part.

Fourth: Clean up the motor shell. Also get all the dirt out of there 
where the magnet will re-attach. Hopefully the other magnet is still 
good. If both fell out well clean everything.

Fifth: Get your magnet gauges and test fit the magnet. I made three of 
them out of plywood stock: Two for the sides and one that goes across 
the center. Cut the wood and test fit it with a good motor (you have two 
more), you want them to be tight but not too tight. Taper them a bit, 
and sand the edges for a perfect snug fit.

Sixth: Mix up JB Weld. I like to use a large nail as I can goop it on 
the back of the magnet then use the nail to smooth it out. Nice smooth 
amount. Then take the rest of the JB Weld, put it on a paper towel, and 
put a thin layer in the motor housing where the magnet was. Always best 
to have JB-JB without voids....

If the magnet is broken put JB weld on each side of each break but don't 
assemble the magnet here, do it in the shell.

Seventh: Install the magnet with the side gauges, and get it to the 
right depth. Match the other magnet. If both were bad you have to move 
fast to get both magnets in and to the right depth, but note that your 
side gauges will hold them in nicely. Then once aligned tap in your 
center spacer to press the magnets against the wall.

If the magnets were broken this is when you re-attach them. Let the side 
gauges press in and hold it all together and push them in tightly. The 
JB will bind the magnet to itself and to the wall. Then put in the 
center spacer, try not to be right on the crack if possible.

https://i.imgur.com/SLxnotX.jpg

Let it dry for 24 hours and re-assemble. I've done this on large mower 
magnets, and the large drive motors that ran the E8/10/12 and the leaf 
blower (note they can use up to 4 magnets).

It's a job but it's got to be done. I've had failures in old motors and 
the new rebuilt ones that Bill Gunn did. I think the root problem is the 
crappy tape they used to secure them and they will all probably fail. 
I've never had a JB Welded one fail and I think I did my first one 20 
years ago or so.

Chris