No joy, I took the 4 fuses out and re-checked, all ok.
2A Battery Fuse
2A AC Fuse
1A Aux Fuse
1A Bell Fuse
I am getting approx 14v at each PIR and the tamper operates, I am just getting an open loop at pir on the N/C terminals, I linked these out to prove the cores ok and they were. Strange...