Abrahamsson Rapidwinder
Let's take a look at it and how to take it apart
Abrahamsson Rapidwinder is a re-imagining of the Leicavit Rapid wind accessory. You can find better information about the history from smarter people than me elsewhere on the internet. So instead let's do what I could not find done anywhere else as public information – take it apart.
Your Rapidwinder probably doesn't quite look like the one shown here – mine is an IXMOO compatible M6/M4 Rapidwinder. This is also a "Super Deluxe RapidWinder" with the stainless steel drive mechanism, but that is only relevant after it is opened. The IXMOO opener has also been modified to accept Nikon reloadable film cassettes by the previous owner, so it looks a bit rough. The three additional screw holes visible in the end were done by the previous owner as well, they are even less relevant for our purposes.
First we will remove the screw on top of the plastic "tulip" part. I know the tulip is actually the part inside the camera, but you know what I mean.
Next, unscrew the screw under the film cassette holder / swiveling door lock. This part will look different on most winders, but the screw location should be identical. The screw is located horizontally underneath the part. Rotate the door lock to better orient the screw for removal. You don't need to completely remove the screw, but you can if you want.
It should look like this. At this point, the door lock switch should fall out from the bottom. Don't lose the washer if your example has one.
Door lock switch removed as well. Observe that it is possible to install the lock switch in two directions rotated by 180 degrees. If you install it the wrong way around, the locked/unlocked indicator won't match up on the bottom of the camera.
Next we have to unscrew this brass part that the "tulip" was screwed onto. Depending on how stuck yours is, you can either get it off with a good grip from thick rubber gloves...
... or protection and grip from a section of bicycle inner tube and big pliers like I did. It unscrews counterclockwise like any other screw.
The plate should now be free to lift off. If it is hesitant, you can clean the corners with a wooden stick or cotton bud if there is lots of accumulated crud preventing lift off. I had to use some force with tiny pliers on the film guide ridge. If you use the film guide ridge, be sure to lift straight up. Don't bend anything.
After the plate is removed, you get access to all the goodies inside. As you can see, there was oil and dirt everywhere on my copy. Don't play around with the charging handle with the lid removed, as there is nothing to stop it from lifting out of its rails.
This drive sprocket that the belt loops around is stainless steel on the "Super Deluxe" models as pictured here, and brass otherwise. They all look silvery on the top, so you will only know after getting to this point. Apparently the number of stainless steel ones are c. 30 units, so expect to see brass here. Also visible in the lower left are the three extra holes in front of this particular winder, they are for a front-grip.
Assembly, as they say, is the reverse of disassembly. If the locked/unlocked indicator doesn't match the spot, loosen the screw under the door lock again and flip it around 180 degrees.
In contrast to my otherwise laissez-faire attitude towards anything in general, I have to include the following serious bit: Information on this page is provided as-is, no guarantee of it being correct. If something breaks or other bad things happen, it was your own fault. Don't do anything you see here if are not sure about what you are doing.