Multo ADDO model 13
These calculators have a bit of a bad reputation, and not entirely undeserved. It is famously quoted as "the rarest pinwheel calculator" because almost no examples are left that work, due to zinc rot.
If fact, I have three of them, none of them subject to zinc rot, but only one of which briefly ever worked (this one, in fact). Another one I got, new in its original shipping box with the original manual, but it was blocked right from the start, it's been sitting around disassembled for years now, and I've never gotten around to trying to repair it. This one is in good nick too, however, so I've taken the freedom to marry it to the box I have fro the other one. That one is grey, and has a serial number in the 38000 range, whereas this one is 42 960. The number stenciled on the box is 58170, which is different again - so either it is entirely unrelated to what machine was in there, or the box I have is not original to the machine I got with it either.
So here's the box:
Looking inside ...
And with the machine out of it, showing the cotton padding:
Moving on to the machine itself then:
And the underside with the serial nr.:
This is the grey machine that came with the box:
And finally a video to demonstrate that the machine is indeed working:
So what is the issue ? The construction appears to be so hideously overcomplicated that there is always something prone to go wrong somewhere, either in the carriage movement, which is a nightmare assembly of springs and levers that essentially falls apart when you take the bottom off the machine to look what's wrong with it, to the clearing of the carriage. In this particular machine, clearing the result register or backtransfering the result up into the setting register a bit too vigorously will for some reason pop up the tens' carry arms, so that will block the carriage in its current location and necessitate the cover to come off the machine in order to push them back down to unblock it. So a moment of carelessness in use will cause at least five minutes of disassembly - calculating with this machine as it is is like running around with a live grenade really ... the clearing requires a light touch!