On 2 Aug 2004 05:10:19 -0700, snipped-for-privacy@ukgateway.net (Gel) strung together this:
Any ideas as to what material would work please??
A new PIR. The plastic lens on the front of a pir is a lens, not just a piece of random plastic. For what a new PIR costs, and for the fact that if the plastic has gone brittle then the PIR is probably old enough to be a candidate for failure soon, I'd just replace it.