Band of Missing PLA in Print

The following was printed on a Rostock Mini along with a second STL that failed due to the 4-6 mm of filament starvation seen in the photo above the nose but below eye line. Due to the curves in the print it seems to be holding.

I am assuming that there was a temporary clog in my E3D v6 causing the lack of filament in the print, but I wanted to get a second opinion and see if anyone has any suggestions for avoiding this in the future.

Also, does anyone have any thoughts for reinforcing the gap or should I just plan to reprint the piece?

Thanks for the help, have a good week.

Most likely was an extruder problem, PLA and all metal hotends tend to develope issues, even with an original e3d v6.

Several things can be done to prevent future problems:
1.- correct temperature. What temperature did you used?
2.- Extrusion rate.
3.- clean extruder gears before start printing.
4.- clean nozzle before printing and after material changes.
5.- extruder tension, chech that the gear grab firm the filament.
6.- printing speed to temperature "ratio" the faster you print the higher the temperature needs to be and vice versa.
7.- PLA cooling fan might be cooling the nozzle.

As you can see, several things might be at fault, thats why the awful and tedious task of observation it is still so important to spot a problem and understand why happened and how to prevent it.

Also check and make sure your spool doesn't catch on anything or get tangled. Some spool holders are too low friction and the filament can unwind randomly and come off the spool and catch on stuff. As small amount of friction in your spool holder keeps the filament wound on the spool and prevents tangles.