After 45 years of abuse and plastic spacers within the door handle, those spacers broke. Some where already missing and the door handle was shifting inwards and hammering against the wood.
The plastic itself was brittle and worn, so a replacement was required. Unlike the original I printed the new spacer in TPU, which also absorbs bumps and makes the handle more silent.
This is a fairly simple design, but this may help others.
I included the FreeCAD source file to adapt the parametric design using the included spreadsheet.