TIA: I found out, on this forum, that the limit straps do come either as a unit (about 68 american dollars from
www.centerlinealfa.com) or just a strap for about 10 dollars.
Since my entire units were missing, I elected for the units (pictured). Upon getting them, I figured out that to install it, you need to knock the pin out of the door hinge to release the strap. then you need to take the door panels off and unscrew the bolts INSIDE the well that the strap disappears into. The unit then comes off from the inside of the door (at least on my '78 spider).
A practical point in removing the device; I had to take off the doors to get to the bolts holding it in place. A bit of a chore, but not too hard.
Try taking it apart- you may just need the strap... Ger