One weird trick for making a cotter pin

The left Magic Margin stop on a customer's Royal Quiet De Luxe wasn't working. When I peeked at it, the problem was evident.

I removed the carriage's back panel and took a closer look.

Evidently, the device had lost a screw like the one you can see here on the right margin stop.

Did I have such a screw? No. But I realized that the problem might be solvable with a cotter pin, also known as a split pin.

Here's where the magic of paper clips comes in. They are easy to bend, but very unlikely to break unless you bend them repeatedly back and forth. I've used them to replace the C-shaped links that connect the type lever to the typebar on Olympia portables. I realized I could also use a paper clip to make a cotter pin. Using pliers, I bent the wire around a thin cylinder (the shaft of a spring hook) to create a loop. One end of the cotter pin should extend farther than the other, to make it easier to insert it into a small hole and easier to bend the tip once it's through the hole. 

The next step was to line up the holes in the margin stop, placing the spring onto the right end of the lower piece.

I worked the cotter pin through the holes, and then used a screwdriver to bend the tip of the pin.

The pin holds just fine, and the margin stop is fully functional again. Job done!