diff --git a/script/local.py b/script/local.py
index b1800f0..dec4048 100644
--- a/script/local.py
+++ b/script/local.py
@@ -55,6 +55,6 @@ def fit(ydata, xdata = None):
     else:
         p.addMarker(max_x, None, "Max="+str(round(max_x,2)), Color.Gray)
         print "Invalid gaussian fit: " +  str(mean)
-    
+        return (None, None, None)
 
 #fit([1,2,3, 3,3,3,4,5,6,12,33,23,15,3,2,1, 1, 1, 1, 1])        
diff --git a/script/rock.py b/script/rock.py
index 4948790..3dc2fc0 100644
--- a/script/rock.py
+++ b/script/rock.py
@@ -28,8 +28,17 @@ def rock(axis = th1, ffail = False, tt = 0.2, seti0 = False, dx = None, noref =
     #MVR,axis,-dx
     #SCAN,axis,0,2*dx,20,/fit,/centre,SILENT = silent,FFAIL = ffail,time=tt,/deriv,$
     #data=d
+    axis_pos = axis.read()
     lscan(axis, beam_ref, -dx, dx, 20, latency = 0.3, relative = True, context = None, before_read = None, after_read = None)
-    LSCAN()
+    (ydata, xdata) = (result.getReadable(0), result.getPositions(0))
+    (norm, mean, sigma) = fit(ydata, xdata) 
+    if (mean is not None) and (mean <= (axis_po + dx))  and  (mean >= (axis_po - dx)):
+        caput(axis, mean)
+    else
+        print 'fit failed - centering on maximum'
+        max_x= xdata[ydata.index(max(ydata))]        
+        caput(axis, max_x)
+    
 
     if seti0 and not ffail:
 	    time.sleep(2)