Probably McMaster-Car. I thought about them as well, which is why I asked about the size/pitch of the "screw" I thought I was missing. I do a lot of tinkering on various things and virtually nobody makes their own fasteners, but MC is likely to have them if you know what to buy.
It could be worth getting a metric screw pitch gage like here. Put thread against it, hold up t light, esy to find the exact pitch. Diameter usually falls onto a 'whole' number- if it measures 1.42mm, almost certain 1.4mm is its name (threading has variation in actual dimensions from both design and manufacturing tolerances).
Screw Pitch Gages measure inch, mm, whitworth threads
(good company, by the way, with most things cheaper than McMaster since they aren't trying to do everything for everybody)
Although custom screws are common, standard thread pitch and diameter is also quite common. I've used screws from a Rollei on a Minolta TLR. On and on.
Knew someone who was an antique gun collector and restorer. Pre-Civil War American guns were his specialty. He could cut threads at any number you'd throw at him. As he explained, before the Cvil War, a machinist didn't care if his threading matched anyone else's. He made what he needed and got on with it. But the war brought about mass production at a variety of locations. A part made in Vermont had to fit a part made in Connecticut. No more making your own threads, you worked to specifications.