A Monroe electromechanical calculator

I know, I didn't give an update this week. I've mostly been lazy this week. I've been playing with an electromechanical Monroe calculator. My dad brought one home when I was, oh I don't know, ten or so. I played with it a while, and then I wanted to see how it worked. I remember opening it up and being confronted with this mass of levers and gears, and I knew that I had absolutely no hope of understanding the thing.

So recently I got one off eBay. It's semi-motorized, has eight columns of buttons, and a 17-digit accumulator, with two other 8-digit registers on top. It can multiply and divide. When I plugged it in, it would turn over sometimes, but more often not. It also smelled like electric burnination, which isn't good. So, like I did way back then, I decided to open it up.

I was so careful, and yet I managed to break off the main knob, the circular thing in the image to the right. It's clear that there weren't any set screws or anything else holding the knob on its shaft, so I pried it loose. Well, apparently prying is the correct thing to do, but unfortunately I must have fatigued the metal shaft because it broke off. Perhaps I'll get lucky and find another one with a good shaft.

Anyway, I opened it up and I was confronted with this mass of levers and gears:

But, armed with decades more experience, and a bazillion tools, and Teh Intarwebz, I knew that I could finally dig into this, and figure out why it wasn't working. I have not yet been able to find the service manual for this thing (an MA4-170, which is one of the many, many Model 1 series Monroe made). However, I was able to dig online into Monroe's patents, and find matching diagrams and descriptions, as shown:

It's not perfect, because the reality is that these things have all sorts of fiddly little adjustments that need to be made. So a service manual would be ideal.