diff --git a/parts.scad b/parts.scad
index 0cff8e0..384ace0 100644
--- a/parts.scad
+++ b/parts.scad
@@ -125,14 +125,14 @@ module ysled_slider(spread, associated_parts = $preview, is_left=true) {
 
   // color("#f00")
   translate(
-      [ pulley_sbend_offset - yrail_offset + motor_shaft_xoffset, 0, 0 ]) {
+      [ pulley_sbend_offset - yrail_offset + motor_shaft_xoffset, 0, frame_size/2 ]) {
     translate([ 0, idler_spacing / 2, 0 ]) {
-      idler_post(belt_height = belt_height1, toothed = is_left);
+      idler_post(belt_height = belt_height1 - frame_size/2, toothed = is_left);
     }
     translate([ 0, -idler_spacing / 2, 0 ]) {
       *cylinder(d = 3, h = 30, $fs = 1);
       *idler(belt_height2);
-      rotate([ 0, 0, -90 ]) { idler_post(belt_height = belt_height2, toothed = !is_left); }
+      rotate([ 0, 0, -90 ]) { idler_post(belt_height = belt_height2 - frame_size/2, toothed = !is_left); }
     }
   }
 
@@ -288,6 +288,13 @@ module blcorner() {
     corner_base();
     rail_holder(true);
   }
+  translate([motor_shaft_xoffset + pulley_sbend_offset, 0, 0])
+  rotate([0,0,-90])
+  idler_post(belt_height = belt_height1, toothed=true);
+
+  translate([0, -(motor_shaft_xoffset + pulley_sbend_offset), 0])
+  rotate([0,0,-90])
+  idler_post(belt_height = belt_height2, toothed=true);
 }
 
 module brcorner() {
@@ -297,6 +304,13 @@ module brcorner() {
     corner_base();
     rail_holder(false);
   }
+  translate([-(motor_shaft_xoffset + pulley_sbend_offset), 0, 0])
+  rotate([0,0,180])
+  idler_post(belt_height = belt_height2, toothed=true);
+
+  translate([0, -(motor_shaft_xoffset + pulley_sbend_offset), 0])
+  rotate([0,0,180])
+  idler_post(belt_height = belt_height1, toothed=true);
 }
 
 module xsled_slider() {