UPDATE March 2019

So my friend informs me that the REV04 part failed Mid March 2019 so at least three months working time. I have uploaded another part with some re-enforcement see Rev05. Hopefully stronger. The part that failed was only printed in PLA so not bad.
I think this part is best to be printed in ABS or Nylon.

Original Text

This design was a quick fix for a broken Car Door Electric Window mechanism on a Saab 95 Estate Year=2005 approx.
Note: this rail runner maybe common to other cars.

Symptoms:
Door Window glass had dropped into the door while driving.
Inspection after removal of door card showed the rear rail runner which connect to the electric window scissor jack had failed. The rail runner supports the window glass and the plastic material had decayed to the extent of releasing the securing pin. The green plastic wheel with black grease is the original part and the grey is 3D printed replacement. See pictures.

Fix:
Print the part in open scad file. Note this may need some changes to the tolerance. Best print one to gauge fit and then adjust or file or sand accordingly to fit in the rail. Use digital calipers to measure the original against replacement. Try and get as close as possible to the size. When size is good grease the printed wheel and push the secure pin partly on ready to attach.

Attachment and Assembly:
Get some gloves (metal is sharp), a torch, a mirror (to look up inside door cavity) and some needle pliers to push secure clip on. Ideal to have two people one to hold glass and other to jog motor and attach the runner mechanism. If on your own use gaffer tape
to hold the glass.

Now There are two rails that connect the scissor jack to support window glass. A Front rail and Rear rail.
Reposition the Window in the door such that it is in the correct slot/groove of the rubber
and ensure the front wheel runner is engaged to the front rail. In our case the glass had
dropped out completely out of front rail runner. You may need to tip glass at an angle to
re-connect the front rail.

Then with some jogging of the electric motor to bring the rear rail into view through the door panel opening, slide the wheel on to rail and attach the rear wheel runner to scissor jack end with the clip. Its a ball and clip connection.

Then jog the window motor slowly ensuring there is no resistance. Motor should move window with ease. If not inspect window glass to door.

See pictures.

There is one picture showing the scissor jack.