Amiga 1200 keyboard ribbons

[Castellen]

True, could be hard finding replacement membranes.
Possibly try the likes of SoftHut and Eyetech?

Or try a Google search.  If there's a buyer, there's often a seller :-)

[Castellen]

Unlikely.  The ribbon is all part of the keyboard membrane, custom made for the A1200.
You might be able to find that flex-loom similar to the plug in section somewhere else, but joining it to the old one would be a major mission.

The conductive tracks inside it melt away if you try to solder it.  Yes, I've tried to fix them too :-)
Conductive paint/glue is a possible fix but would be nearly impossible to make a reliable join in every track.