This event took place at the San Mateo Library.

I mainly spent the 3 hours working on a broken IBM Selectric typewriter; I’ve had some experience restoring manual typewriters. The owner had taken it to a repair shop because the keys were a bit sticky, and it had come back broken. It appears the repairman had put a lot of oil and grease in the typewriter, which had gummed some things up.

Wikipedia has a detailed description of the Selectric’s mechanism here, though it’s rather meaningless unless you have it in front of you to look at. So I’ll give a general overview of its theory of operation:

The IBM Selectric is not really an “electric” typewriter, at least not in the sense that it is electrically controlled. I would describe it more as a “powered typewriter”, in that it is controlled mechanically but powered by an electric motor rather than the user’s fingers. That said, its control mechanism bears some similarity to digital electronics in that it converts each key press into a binary signal and then into an analog twisting and tilting movement of the type-ball to print the selected letter.

Basically, each key is mapped to a combination of “selector bails”, which are activated by pushing them towards the front of the machine. An “interposer” matched to each key pushes the correct selector bails by way of a powered mechanism that requires only a light key press to activate. The selector bails are the inputs to another powered mechanism that ultimately uses a whippletree to convert the digital input to an analog signal that is transferred to the print head.

At any rate, I didn’t know this going into the repair. I thought that the keyboard was just “gummed up” badly and needed some degreasing with alcohol, which I proceeded to do. After plugging it in to test, we noticed that something was seriously wrong since the machine was continuously advancing the platen. The return key was stuck, but even when we pulled it back up the machine couldn’t type and key travel was severely limited, indicating that something else was wrong.

We basically spent the whole time trying to unstick various mechanisms, none of which repaired the machine in any meaningful way. Aside from the keyboard being extremely jammed up, the carriage was also very difficult to move, as were a lot of the mechanical linkages inside. I didn’t realize until right before the event’s end that the keys weren’t meant to directly push the interposers, so I spent a lot of time trying to un-jam the little pawls attached to each key thinking that they’d be able to wedge the interposer forward when unstuck.

A proper repair would have most likely meant either complete disassembly or perhaps just spraying the inside with a lot of brake cleaner. Wikipedia says that these machines required frequent maintenance by skilled technicians, so I doubt that the people from the Fixit Clinic could complete the repair in just three hours unless they had prior experience or at the very least a working Selectric to look at. That said, the machine was really easy to take apart and exterior covers all came off by way of spring-loaded latches, at least eliminating one significant step in the repair.

In comparison to manual typewriters, I’d say that this machine is a lot harder to repair. While a manual typewriter may seem complicated, at least the key mechanism is highly intuitive — each key is mapped to one type bar. They’re also easier to troubleshoot because you can move things by hand and see what they’re supposed to do, something that’s much harder with a Selectric. From a sentimental standpoint, I suppose manual typewriters represent a bygone era in typing and excite more passion from typewriter enthusiasts since they represent a radically different aesthetic and typing feel from computer keyboards, though as I’ve mentioned the Selectric is in operation more similar to a manual than a computer.

Something interesting was that pretty much every person over 50 years old who walked by our table mentioned that they had used one of these typewriters. My dad said that when he used to play on one in his father’s office, and it produced letters much crisper than those of a manual typewriter (because it used a different ribbon).