If you have a Philips Norleco face shaver and are noticing that it is becoming less effective, you may need to replace the shaving head blades with
3 Ways to Disassemble a Shaver - wikiHow Life
Battery Replacement on Philips NorelcoElectric Shaver - 5000
How to change PHILIPS NORELCO SHAVER HEAD BLADES REPLACEMENT - 4K
How do I remove the shaving heads of my Philips Shaver?
Quick Fix: How to Replace the Shaver Heads on a Norelco Electric
Philips Norelco OneBlade Exterior Casing Replacement - iFixit
My brother is looking for a good electric shaver. This was his
Philips Norelco BeardTrimmer 3100 Zoom Lock Precision Notch
Philips Norelco BeardTrimmer 3100 Repair - iFixit