deskthority

I'm in the process of repairing an old Lear Siegler terminal that uses a variant of Futaba Complicated Linear switches that have a slanted top of the shaft (the keyboard and plate are at an angle, the shaft top is slanted so that the key caps are level when installed). I've found a few sources for the standard Futaba switch but not for the ones with the slanted shafts. I figure there has to be another plate-mounted switch with slanted keys that I could use instead. Does anyone know of any?
Here's an image from the wiki for the STM Pied Piper which uses the same Futaba switches (or equivalent) that I'm searching for.

The holes in the plate are circular with small adjacent holes or notches for the locating pegs. If you want to use another switch, you'd have to be OK with cutting a new hole in the plate to accommodate the switch as most of them require rectangular holes.

The example in the image has tall keystems, which are very unusual — they're mostly known from old Apple keyboards (tall Alps and SMK switches along with adapters for shorter switches). I assume yours are the same tall stems? There's not a lot out there that has tall and angled keystems — it's never been seen with SMK, and with Alps there's only one ultra-rare version with tall angled keystems (on sale in Sweden, and several of us have some).

If the damage is a broken keystem and you can't glue it (i.e. the snapped of part is lost along with its keycap), then you're in trouble — the first thing we need is the switch dimensions. There's no reason for the switch to reach the plate (you can connect it with leads) but it has to reach all the way to where the keycap is. (Trying to raise the switch up would be an interesting exercise.)

If the switch has developed internal faults, then you're better off repairing or replacing the internal parts from donor switches. The legs unscrew and pull out, and the internal design is very easy to work on.

Sadly you've found an extremely rare version of that switch series!

Yeah, the switches I have are the same tall and slanted ones seen in the picture. I'd rather not have to modify the plate if I could avoid it since it would mean desoldering every switch on the keyboard to be able to remove the plate. I do have donor switches though - I bought a few of the standard version from a seller on eBay without realizing they weren't a perfect match. I thought about just swapping the keystems but I was under the impression that disassembling the switch would destroy it in the process. If that's not the case then I could probably make that work.

There are full disassembly photos here:

wiki/Futaba_MD_series#Cross_mount_2

Basically, unscrew the legs (requires a good firm grip) and take off the base plug, and slide the parts out. The slider is in two separate parts, for reasons nobody understands — it's one of the weirdest switches I've ever seen, and may still hold the record for the most number of parts.

The one part that may be different is the return spring — the replacements may be a different weight to the original.

Luckily the switches I need to replace are mostly the function keys along the top of the keyboard, and one of the Shift keys, so if there's a slight difference in weight it won't matter to me. I'll definitely have to give this a shot though, I have a bag of 20 of the black & red switches so sacrificing one or two isn't really a big deal since I only need to replace 6 switches on the keyboard.

Just wanted to report back and thank you. Swapping the key stems worked perfectly and the switch went back together with no issues whatsoever

Sadly even back in the 70s, some switch types were not designed to repaired, but it's always very useful when they were!