electric motor replacement for hydraulic headlamp adjuster

Following a helpful post by Arnie (thanks - your posts are invariably full of useful comments) some months ago I ordered the electric motors from the German supplier.  The motors are fine and easy to fit provided that you follow the diagrams on the supplier's website which explain how to reduce the size of the plastic mounting rings that are attached to the headlight unit. The German text is needlessly complex (one sentence  is six lines long with a number of subsidiary clauses within it and best avoided - just go with the diagrams).  I connected the motors and the control unit's red wire to the grey wires that go to the parking lights and it works fine but I'm not certain that this is how you are supposed to do it. The control unit to be fitted to the dash is supplied with a plain knob to replace the original knob.  This is less than satisfactory if you want to preserve the original appearance.  My solution was to adapt the components of the original hydraulic unit to enable the original knob to be retained.  The friction that results on turning the knob is exactly the same as when it was hydraulic and you wouldn't know that it was different.  Stages are as follows, and although a lathe was used I think a combination of a Dremel, penknife, and files would do as well.  My vehicle is a 300GEL and I don't know whether this hydraulic system is common throughout the range.

1.  Remove the dash panel, cut the hydraulic pipes with wire snips and removed the hydraulic unit which is held in place by a metal locking ring which needs to be saved for reuse.

2.  Remove the plastic threaded part from the unit that the knob engages on together with its surrounding internally threaded ring which has two lugs which drive the pistons when the knob is turned.

3.  Place hydraulic unit in vice and using a fine-toothed woodsaw cut through the unit. The part with the pistons and tubes is discarded, the other part is then placed in the lathe and the internal bore slightly enlarged so that the new control unit fits in it exactly.  Probably only 0.5mm needs to be removed and this could be done with files/Dremel as long as the two longitudinal ribs ( about 1.5mm square) that prevent the ring with the lugs from rotating are removed.

4.  The two parts with the screw threads are put together, placed  in a vice, and using a woodsaw the lugs are removed and the overall length slightly reduced.  A 6mm hole to accept the shaft of the control knob is then made down the middle.

5.  To eliminate in and out play on the original knob and  prevent it being pulled off, a washer was placed in the lathe and the internal diameter enlarged until it was an exact fit for the shaft of the original control knob.

6.  The whole thing can then be assembled in order to gauge how much to saw off the control unit spindle unit (about 8mm  I think it was) and with the spindle  turned maximally clockwise  the control unit is orientated so that this off position is at 12 o'clock.    You will notice that with the knob correctly orientated, the control unit in the off (max clockwise position) that there is a hole in the side of the threaded part that points to the left.  The shaft of the control unit can be marked through this hole.  The control unit is then removed , placed in vice, and a 2mm drill used to make a depression in the shaft into which a fat screw (you're bound to have one in your garage somewhere) is passed through the hole in the plastic to engage with the control knob.    Its obvious when you put it together but sounds complicated in text.

7.  Lastly assemble on the dash panel but before clicking the knob into place make sure the metal hexagonal locking ring is in place and that the washer is over the shaft of the control knob.  Click it all together, insert the fat screw, and then super glue the body of the control unit into the housing that was enlarged to fit in 3 . Don't get glue on the part that needs to be free to rotate in the housing.  Job done.

I'll try to attach a picture which shows where to cut the housing, and the position of the screw and the washer once assembled (knob rotated a bit so that the screw shows).