I'm not expert but my guess is that spring is tempered steel. You could probably hit the spot you want to drill with a propane torch long enough to get it a bright orange. Then drill the hole. After you are done with the hole, torch it again until it is cherry red (a dark red, not bright), then dunk it in either water, or transmission fluid (most things are quenched in hot oil, but water should be fine in this case). After you have quenched it, heat it again until it turns a dark blue. The blue will come about fairly quickly, so be prepared for it. After is has blued, set it aside and let it slowly air cool.

The first step will soften the metal. The last two steps will re-temper it. Hope this helps.

Sorry for all the replies, but I can't for the life of me figure out how to edit my posts. Anyway, I don't know if you have any of tools to do this suggestion or not, but if you go this route, be advised that when the spring is heated to a bright orange the metal will become VERY soft, and can buckle under its own weight, so it's best if you could have just that portion in a bench vise or something, so when you heat it it will not have the added stress of the weight of the spring pulling on it. Hope this makes sense.

I was referring to one of these a "Propane Torch" here in the US. If the Bunsen Burner is capable of heating the metal to the appropriate colors, then it should work fine as well.

You might want to wait a little and see if anyone else had some suggestions, there might be a better way. One thing I suggest though is to find a piece of metal similar in thickness and practice with it, so you can see the color changes. For the "blue" you can move the torch or burner to "chase" the color.

This is not at all a critical application, so I wouldn't worry too much about messing it up. Hacksaw blades, coping saw blades, or any other thin metal like that are perfect to practice on once you sand the paint off of them. When you apply heat to metal there is a rainbow of colors that occur. Some come about fast, others are slower if you do not have adequate heat. You can tell if you have reached the right color bright orange because a magnet will not be attracted to it, metal actually loses its magnetic properties at that heat. You should not need a magnet though, as any temperatures near that color should break the temper and soften the metal enough for you to drill a hole in it.

Metallurgy and blacksmithing have always fascinated me. The entire process of softening, hardening and annealing basically rearranges the microscopic crystalline structure of the metal. If the metal is soft, it will bend. If the metal is left hard, it will shatter easily (like a file). Once annealed, it has both properties of being hard, yet it will give a little so it won't break.

I think it is easier/cheaper to get hold of a propane torch than of a drill press. I have just started my endevour in typewriter repairs and thus am lacking all those cool tools you guys have...

I'll try your earlier suggestion and report back whether I was successful or burned my flat down. ;-)

Thank you for your tips!
sirius

I remember way back early in my "career" as a typewriter hobbyist.  I was working with a 1936 Remington Noiseless portable, and had the same problem.  I could NOT get that spring to stay on no matter what I did!!  I'm beginning to think that once it's broken, you might as well get another spring drum out of a junker.  But having this problem is a rarity--in fact, that one was the only time a spring drum gave me trouble.