diff --git a/PARAM/HMS/CER/hcer.param b/PARAM/HMS/CER/hcer.param
index a66e390a903b6bc6052762e9ffccbfd94045ee4b..c886b151907c039a5b929abf45cf1c6d372aab7d 100644
--- a/PARAM/HMS/CER/hcer.param
+++ b/PARAM/HMS/CER/hcer.param
@@ -11,7 +11,7 @@ hcer_beta_max = 1.2
 hcer_et_min = 0.95
 hcer_et_max = 5.0
 
-hcer_mirror_zpos = 230
+hcer_mirror_zpos = 230.0
 
 ; hcer_region: 8 values for each region (1 per mirror + sum)
 ; central x,y,dx,dy values and x,y,dx,dy half widths.
diff --git a/PARAM/SHMS/HGCER/phgcer.param b/PARAM/SHMS/HGCER/phgcer.param
index 84eed4d4932a4e177bfe580aeab873c173777129..8ed7833eef28fbb7b5167da57c4128bd280cc5de 100644
--- a/PARAM/SHMS/HGCER/phgcer.param
+++ b/PARAM/SHMS/HGCER/phgcer.param
@@ -12,7 +12,8 @@ phgcer_beta_max = 1.2
 phgcer_et_min = 0.95
 phgcer_et_max = 5.0
 
-phgcer_mirror_zpos = 230
+; Guess from Dwg. 67165-E-00001 R0
+phgcer_mirror_zpos = 175.1
 
 ; phgcer_region: 8 values for each region (1 per mirror + sum)
 ; central x,y,dx,dy values and x,y,dx,dy half widths.
diff --git a/PARAM/SHMS/NGCER/pngcer.param b/PARAM/SHMS/NGCER/pngcer.param
index 8a4062abdf1fffb3574fcbc1731eb335c1866307..54181140d6078338a6f948e801536b81cadc9b32 100644
--- a/PARAM/SHMS/NGCER/pngcer.param
+++ b/PARAM/SHMS/NGCER/pngcer.param
@@ -11,7 +11,8 @@ pngcer_beta_max = 1.2
 pngcer_et_min = 0.95
 pngcer_et_max = 5.0
 
-pngcer_mirror_zpos = 230
+; Guess from Dwg. 67165-E-00001 R0
+pngcer_mirror_zpos = -89.1 
 
 ; pngcer_region: 8 values for each region (1 per mirror + sum)
 ; central x,y,dx,dy values and x,y,dx,dy half widths.