Pinlock - misting up

Just wondering if anyone has any tips for reviving a Pinlock anti mist insert? Been in use for around 18 months but it’s just started to mist up. Have taken it off, cleaned it and the visor, and put it back, but
can’t get the silicon seal to actually seal. Have also tried to flatten it under a pile of books overnight, and I’ve fiddled with those eccentric pins, but no joy.
I have no idea how long one of these things should last - is 18 months a good life? Any tips much appreciated.

Just get a new one. I ordered an Arai one from Ebay, 14 quid and it works perfectly. Old one is totally bent and tried to flatten it as well but doesn’t seem to work.