diff --git a/site_ansto/instrument/kookaburra/config/anticollider/acscript.txt b/site_ansto/instrument/kookaburra/config/anticollider/acscript.txt
index 8ab23c54..a2c963ba 100644
--- a/site_ansto/instrument/kookaburra/config/anticollider/acscript.txt
+++ b/site_ansto/instrument/kookaburra/config/anticollider/acscript.txt
@@ -1,4 +1,9 @@
-# Forbid detector motion when the detector voltage is on
-# comment out -- Jing
-#forbid {-inf inf} for det    when dhv1 in {800 inf}
-#forbid {-inf inf} for detoff when dhv1 in {800 inf}
+# Prevent m2om encoder from driving into sample holder.
+forbid {10 inf} for m2om whenall {m2y in {-inf 200} m2om in {-inf 10}}
+forbid {-inf 170} for m2om whenall {m2y in {-inf 200} m2om in {170 inf}}
+forbid {-inf inf} for m2om whenall {m2y in {-inf 200} m2om in {11 169}}
+forbid {-inf 200} for m2y when m2om in {10 170}
+
+# Following two rules allow recovery if m2om position has crept above 10 or below 170
+forbid {11 inf} for m2om whenall {m2y in {-inf 200} m2om in {10 11}}
+forbid {-inf 169} for m2om whenall {m2y in {-inf 200} m2om in {169 170}}