: Instead of opening the PDF directly in Illustrator, Place the file into a new document. Then, use Object > Flatten Transparency and check "Outline Text" to turn the missing fonts into shapes you can at least see and move.
(like HP-GL, Gerber, or CNC): Those F1–F4 fonts are often built into the device firmware — they can't be downloaded separately. Check your device manual. cid font f1 f2 f3 f4 free download free
The Mystery of CIDFont F1, F2, F3, and F4: What They Are and Why You Can’t "Download" Them : Instead of opening the PDF directly in
: If you don't need to edit the words, use a tool like Acrobat’s use a tool like Acrobat’s