I had the same problem in my 240D. If you can get the tumbler out, use a big screw driver and see if you can turn the ign switch on the column. If it turns and starts, the problem is in the tumbler not turning all the way. I was able to fix my tumbler by washing it repeatedly in Zep Citrus cleaner to get the sticky gunk out. The gunk was what caused my tumbler to jam and not turn all the way.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked