To fix the shifter, pull off the leather gaitor then pull out the thick rubber o-ring heat/sound insulation. Then get under the car. Look for the gearbox housing then follow the link rods back up towards the passenger cabin.
You should see a join where a rod running the length of the car connects to another rod that goes up into the cabin. To get at this you might have to remove the prop shaft cover. I had to replace a bearing that went under here. At the join of the two rods, you need to remove a c-shaped retaining clip, then you can detach the vertical rod which is your shifter.
You can get another shifter from a bmw dealer, i don't know what the part code is but someone here will. Otherwise, well, there's only one gear shifter in the car so they can't really order in the wrong bit!
I think that's right, I might have forgotten a couple of small details but nothing major. Um if you've not worked on a car before and are serious about fixing this yourself (it's pretty easy just can be a bit awkard and dirty) support the car properly with ramps or axle stands!
Gone but not forgotten: '87 UK 318... Carb madness!
Currently: '90 UK 525i completely stock
"Heaven for the climate, Hell for the company."