All the methods mentioned above depends on material of Your Fritz speaker tweeter material.
1. Be: Berilium a metal it may not work, or need more powerful glue tape.
2. Also can use a small tube and Mouth suck to pull at the dent,
3.A pin and glue to pull the dent and dissolve the glue suitable water/solvent.
4. all Vacuum cleaner has bleed to control suction power.
All the best

