open vbscript Editor, Mainmenue    Operator -> VB Script Editor

then copy/paste this code into the Editor

Code: [Select]

DoButton( 24 )
While IsMoving
Wend
code"(Z Axis is Referenced)"
code"G4 P.1"


DoButton( 22 )
While IsMoving
Wend
code"(X Axis is Referenced)"
code"G4 P.1"


RefCombination ( 10 )
While IsMoving
Wend
code"(Y Axis is Referenced)"
code"G4 P.1"

While IsMoving
Wend

If(GetOEMLED(23)=false) Then 'This will turn on the softlimits on
  DoOEMButton(119)
End If
While IsMoving
Wend

code"(All Axis are Referenced)"
While IsMoving
Wend

code"G4 P.1"
While IsMoving
Wend

Code"(Moving to Home Position)"
Code"G28"
While IsMoving
Wend

DoButton(7)
While IsMoving
Wend

Code"G4 P.1"
While IsMoving
Wend

Code"(X and Y axis are Homed and Zeroed)"

use the >|| button (Step Into Script) to run code line by line and see where the jitter happens.

BTW, do you have any values in

Config -> Homing/Limits -> Home Off. ?

OK will give it a go and report back and let you know about those values.