Proximity switch aluminium bracket causing interference

[squints]

Aluminium bracket has been interfering with our proximity switches.
Our theory was to use aluminium because it is not magnetic.
It seems we were wrong.
Replaced it with a hard plastic and now have a 1/4" more play.
The switch would open at about 1/4" away from the haul rope and now opens at about 1/2".
Quite the difference.



Above: Bracket that was removed





Replaced with hard plastic