leaking fuel hoses....
I hear you all as my '77 is the the same way (new injectors, and replaced lines)
FWIW, I had wondered previously with my car if the hoses (which seem to be a semi-soft metal) became mildly cross-threaded if they're not seated just right when screwed on *shrug*. The injectors (aside from spotty re-build quality) seem to be pretty sturdy on the threaded ends. I can't speak for W124's though.
I still see a slight weeping from two problem injectors/hoses, but funny enough, they seem to come and go (?)
'95 E420 - 'Shadowfax
'92 Volvo 740Turbo Bard
'74 240D - 'Ol' Green
' 4spd Manual 104kmi. (sold
'77 300D - 'Red
' 223kmi (sold)
'75 240D - 'Bianca the Blue Bomber