The repair/mod was carried out on an E36 compact 1999 built year. There is no difference between VFL = pre facelift and FL = facelift models, in both the same parts are installed. Since the original bulb holder with bulb (part number 61138364617) is no longer available, necessity is the mother of invention and the lighting is functional again. The bulb of the BMW socket is not replaceable, because it is cast into the housing. Here comes a tutorial how it works with a new classic bulb and for little money.
This bulb can be replaced at any time because it is removable from the bulb holder. For the renewal you need the following per side:

Required parts:
- 2x flat plug sleeves for example from Hella (8KW 732 566-003) 0,5-1,0mm˛ red (Attention: Color in the picture is partly deceiving in the internet, correct part is red/pink)
- 1x bulb holder with bulb 12V from Hella (9FF 713 627-001)

Hot air dryer (if necessary a lighter will do)
caliper gauge
side cutter
crimping pliers
wire stripper


The first thing you need to do is prepare the lamp socket. As you can see the new one is square, the old one is round. It has to hold in the intended holders of the speedometer cover. Therefore, measure the diameter of the original part with the caliper and grind off the corners of the new part until you get the same diameter. Then you have to remove the speedometer and the light switches. You can find instructions on the internet. Pull the old lights out of the speedometer cover. Try the filed off bulb sockets in the provided holders for accuracy of fit. File until it fits. Then simply pinch off the original lamp socket as shown in the picture.
Now you isolate the cables you cut off a little bit, so that they are exposed. Now you put the cables into the flat receptacles. Use the crimping pliers to press the cables together in the sleeve. Then heat the heat shrink tubing with the hot air gun to insulate the cable.

Here is a view of both sides of a flat plug sleeve. Now insert the lamp socket. (pics see link below)
This is what it looks like when everything is attached correctly. It is not possible to mix up the cables. (pics see link below)
If the bulb is defective, you can replace it by simply pulling it out. The following bulb was installed: Glass base lamp W1,2W ; base W2x4,6d

Translated with (free version)

original German text with pics