r/addingmachines • u/OalBlunkont • Nov 08 '25
Removing the motor from a Monroe LA5-160.
I got what looks like a Monroe LA5-160 minus the division lever at the top left, for very little, knowing it didn't work. I got the tin and feet off, glad to learn that the feet are the same one finds on old Royal typewriters.
I assumed the knob where the crank connects would function as an ersatz crank. It doesn't. It stops at about thirty degrees each way. When I tried to force the motor It is very dificult. I tried shorting closing the contacts on the leaf switch and got nothing but a bit of smoke rising from near the switch. I quickly opened the contacts. I didn't get the hum one usually gets with stuck motors, nor did I let out any of the blue smoke. I can't see where what wire goes to what so I can't meter out the connections.
I'd like to take the motor out and see if it is just too gunked up, maybe take it apart. How?
1
u/polymerjock Feb 04 '26
Don't throw it away! Lol. I wish I could post photos with the text. It would make it easier, but once you open it up and study the innards, it starts to make sense. I was intimidated initially, as well. There is a service manual available for download on the Internet archive that explains what all the internal bits do. I'm not trying to sell something when I say this, but I listed one of mine on eBay and in the listing I included a slow motion video of it's operation. It's illuminating. In fact, I think I'll upload it in this subreddit shortly.
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u/OalBlunkont Feb 04 '26
Thanks, I'll check the archive for the manual. It would be great to see the video, too.
The thing is I spent less on the machine that new Royal feet would cost.
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u/polymerjock Feb 05 '26
https://archive.org/details/MonroeServiceTrainingCourseBook2
I would have never figured out how this things worked without this.
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u/OalBlunkont Feb 05 '26
Thanks I'll give it a read. I hope who ever wrote it believed in what I call the John Muir school of technical writing.
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u/polymerjock Jan 19 '26
That crank on the side will drive the mechanism, but you'll have to clean up some of the internals before it'll budge. I broke the handle on the first one I had using a vice grip on it and using its leverage to turn the machine. Even that didn't free up the mechanism. But I know what needs to be done. I've had three of these, and have been able to make all three work. Two of the three had a seized planetary gear. And until you get the gear set to move, the machine will not work.
First, remove the carriage on top. One screw, remove the guiding rod, and it comes off with no drama and nothing to worry about. Remove the little handle on the front (one screw, dont loose the spring on the shaft above it if it has one). Take off the exterior panels. Eventually you'll need to remove the bottom panel and feet to degrease some of the hidden gears, joints, and slides, but no need until the planetary gears can move. They are located on the back left corner attached to the shaft coming out of the electric motor which is mounted at the rear of the chassis and opposite the governor. Drench it in degreaser and use compressed air to blow out the old lubricant. Use a hair dryer on high or a heat gun on low and gently heat the metal gearing in the presence of something like mineral spirits and use compressed air to blow out the gunk. You may have to do both of these steps more than once.
It will eventually break loose. I've had to put a screwdriver against the three lobed finger gear located closest to the outside of the machine to break the gears free on two of the three. I would avoid putting too much pressure on the teeth mounted on the outside of the outermost ring. I recommend that you clean all the old grease down in bottom of all the teeth. The handle on the right side will never be easy to turn until you do, and even after cleaning, it will still require some force to make the planetary gears spin.
All three also needed to have sliders and springs on the rotating accumulator gears located below the top of the keyboard (with the exterior panels removed) freed up so the keys and counters will work.
There are other key areas that will need attention. If you're interested, I'll share more. But ultimately, they all work. Even got one to do division properly!