I would suggest that the liner be peeled back and the foam looked at. Ever wonder why the foam is black? So if it spiderwebs you can see the microcracks as the foam is really white with a black surface coating. An excellent article was published by one of the rags about helmets. Here it is
Motorcycle Helmet Performance: Blowing the Lid Off
3 to 4 years is the recommended life of a helmet. Just so you know where I am coming from, triumph recommends that one disconnect the battery before installing an accessory.



Other factors come into play. Ask yota about the smell angle.

Wearing a helmet because of a law? Then helmets last forever.

Blowing gravel off rural roads