having another look at the machine
running 10min long i found this:
[attachment 99517 orm.jpg]
and a little metal flake on the duet.
I remind having seen a burnt power mod before.
Unfortunatly i cant find this spare on reprapLtd.
But I got questions to your IR sensor:
does it work in the dark?
Does it work on a black surface too?
works just fine on BuildTak (can't recommend BuildTak though, the glue fails)