I'm sure someone has responded to you by now, but here it is anyway: There is a tiny set screw (grub screw it is also called) inside the lever in front. Take that out with a screwdriver and then just push out the pin. If the gum hoods are on they will have to be at least moved aside to allow the pin to come out, but only if they are rather fresh and pliable. Otherwise take them off first. Difficult to do without tearing them. There are little plastic washers in there shaped like a top hat with the top cut out, on either side of the lever when it comes out. Don't lose them. Clean the whole mess and put it back together with a small amount of very light oil or grease. Triflow is fine. They will work like new. Another tip: Put a drop of oil where the spring touches the calipers on either side to prevent that little ink-ink-ink when you use the brakes.
Bob Freeman