Since it is a Super 5 series, this is actually a plunger, which you pull, not a button which you push, correct? If so I may have one. There are two types, both look the same looking right at the end of the platen knob. One is more or less a cone with the shaft of the line release mechanism going into the pointed side of the cone, being secured by a nut. The other is like a hat, but attaches the same way. Which do you have?
Phil Forrest