I might be overlooking the obvious, but I thought I'd post for the benefit of someone searching later my experience with replacing the hall sensor pickup in the bosch distributor on my 86 240 today. The only real problem, is that everything, the bentley, both haynes, the FAQ, searching online, all said pop cap and rotor, black plastic cover, remove circlip, remove shutter wheel, R&R the sensor. I have one from an 83 240, and this is the case. The 86, it is not. As far as I can tell you'd need a PRESS to remove that shutter wheel. There is no circlip or such, and it is tight. What you must do, is remove the distributor, beat the pin out of the drive gear, pull it off and remove the entire shaft from the body, then replace the sensor. Simple, other than if the distributor is stuck like it's welded in, and the drive gear pin isn't much better, and the car's twenty miles away from your big toolbox and bench vice. :)

It took three minutes to re-install and time and have the car running, for what that's worth.