They are leaking from the middle. All of them.

I took apart an injector from a 240D and upon reinstalling it leaked in the middle. Took it back apart and used fine emery cloth on the bottom surface of the upper part. No more leak! Seems that the two halves are a metal to metal seal. there was some corrosion on the upper part and cleaning/resurfacing made a tight seal. Good Luck!

Interesting! I will be trying that. Thanks!