<p> Luis; Try looking at nodevice.com. They sell online repair manuals that one can buy and download in pdf form for Nikon and different other brands of lens, and they have a low res sample of the lens exploded schematic on each lens page. I didn't see your lens listed, but you could look at the ones for the AF 28mm f2.8 and the AF 35mm f2 lens because they are of the same design as your AF 50mm f1.4.</p>
<p> Also. If you do a Google search for Nikon Lens Schematic, you'll find a higher res version of the AF 28mm f2.8 lens to help guide you if you want to attempt a repair yourself. I have repaired many of my lenses over the years with and without these schematics. Hint. Take pictures of every phase of the disassembly to guide you in the reassembly. That's if you want go that rout.</p>