picker, I just replaced four of these links last week, with almost no disassembling and now my SM4 works fine. First one took about an hour while I figured out what to do and the other three went pretty smoothly, Never did figure out how they fell out in the first place---they're well-fitted.

I ended up using a length of wire cut from a T-top straight pin (used in sewing and crafting) because it is stiffer than other wires I had available. There are different thicknesses of these pins; I used the thickest I had and it is considerably thinner than the original links but works fine because it is so stiff. Too soft and you risk the bend opening up with use.

The tricks: 1) figuring out where to put the bends. This is fairly fussy though not terribly so. Too long and the typebar won't make it to the paper. Too short and the typebar won't fall back to lie flat on the rest. I removed one of the original links to measure for a jig and dropped it so I had to replace that one too. Anyway, eyeballing and trial and error did the job. I bent the pin around a small nail to get the bend for the hook gentle enough.

2) Installation needed a long very thin-nose tweezer, a thin screwdriver (to hold things in place while I fiddled with the other tools), and a needle-nose pliers. The trick is to make the bends more open than they will end up being when in place. This is so that they can be finagled through the two holes and then closed a bit with the pliers when they're in place. You will also learn to make the ends of the wire just the right length, short enough so they can be fiddled through the holes but long enough so they will be secure.

Anyway, the only disassembly I needed was to remove the shield behind the keys, two screws right out in the open. I did a lot of tipping the machine on its back to get just the right access and I worked from the top and the bottom. I had removed the ribbon cover for another purpose but not sure you have to for this; still it's only springing the hinge pins a little to get it off so it's probably worth it. If you decide you have to remove the body for enough access, that's pretty easy, too, with four screws on the bottom and easiest if you do it upside down, taking the body off the frame rather than lifting the frame out from the body.

Well worth the effort for this very nice typewriter; very satisfying. Good Luck.

Link replacement went pretty well, thanks to the suggestions from M. Hohne. I replaced the outer one (easier to get to of the two) with a home made version formed from 0.035" stainless wire stolen from an old bass fishing spinner bait lure. For the inner one (5th link in and much harder to get to), after much teeth gnashing, I gave up on trying to get a pre-formed link fitted and finally settled on simply threading some flexible but very tough 0.12" guitar string in a loop though both eyelets, and closing the top of the loop by twisting the ends together. Not pretty but works great. An accidental bonus was an ability to incrementally shorten the link length by increasing the twist in the closure a bit at a time until it fits perfectly. All keys are now working fine, but it still needs some miscellaneous work and a complete cleaning of the entire chassis. The cleaning I'll do before anything further, because there is so much gummed-up and stuck-on eraser dust inside. Since I don't own a large spray-cleaning booth or dunk tank, I'll use my "level 4" dirty typewriter cleaning methodology, namely a 50-50 mixture of distilled water and Dawn dishwashing detergent driven at 70-80 psi from a touch-up gravity feed paint gun, followed by a gentle two hour bake in my wife's oven at 175 degrees or so. In case you're wondering, level 5, which I don't often use, is similar but entails a mix of distilled water and either Krud Kutter power-washing detergent, or (in super-drastic circumstances) Gunk Engine Cleaner. The Gunk is deployed only in extreme instances, and is not left on very long before rinsing, since it will remove some paints and almost any decal. Don't ask how I know.  I do own a small power washer but it's overkill for typewriter work. In any case, selective lubrication is mandatory immediately after the oven drying, because all traces of oil will definitely be gone, fortunately along with all the nasty crud that was stuck to the oil. Surface rust on bare steel parts will set in almost immediately, especially in a humid environment, so don't neglect performing at least a minimal carefully applied follow up lubrication effort.

Lol... Thanks. And don't assume for a minute that I yet know what I'm doing with typewriter repair. Old radios and film cameras, yes, but in typewriter repair I'm in the third grade of elementary school. Certainly didn't mean to encourage folks to load up on oil. I came to typewriters after years of refurbishing film cameras and 40's-60's radio equipment (including many gear-train operated military radios), and I learned the hard way that most oils "travel" like crazy, leaving a sticky dirt-trapping trail like a demented slug. Camera equipment in particular is generally designed to run dry, especially shutters. I admit I do keep a tiny vial of Moebius 8000 around to apply with a sewing needle on rare occasion, but certainly don't recommend liberal use of any lubricant. I wholeheartedly agree that Olympias are great typers. As I've gained more experience, I've sort of narrowed my personal touch typing preferences down to Hermes and Olympia, much like in cameras, where I ended up leaning toward Zeiss, Leica, and Rollei. Back in the day the Germans and the Swiss had things pretty well sorted out where precision machinery was concerned. Hermes 3000's and Oly SM's and SG1's still rule the top of my heap. I haven't tried them all, of course. I do have several S-C and Royal portables that are good typers, but they lack the quiet, brick-solid, precision feel and sound of a Hermes 3000, Olympia SM9, or even the older Olympia carriage shift models like this SM4. To each his own!