Door Strap KerrracK - Cured It!
I've had the dreaded door strap kerrack since I bought my GTV. Replaced the mechanism with the Doblo part recommended elsewhere on here (it does fit perfectly if you use the original arm and remove the plate reinforcement - good work on those threads, guys), but the strap still kerracked, as the noise comes from the joint where the arm is bolted to the wing, not from the mechanism.
On one of the strap threads, someone mentioned that they had heard that winding dental floss into the joint fixes the noise.
I wound a fair quantity, pre greased, into the joint at the top and bottom of the pin. End of kerracking, smooth, silent door operation heaven.
An invisible, totally effective fix for a very annoying problem that will eventually cause the mechanism to fail.
If you've got a kerrack, get flossing.