Android Question Problem with lgBox2DRevoluteJointDef

[noclass1980]

I have been looking at the Box2D_Tumbler example provided with libGDX. I want the rotation to start when the screen is touched. in the LG_Create sub there is the following

rotatebod=False
    'Dim jd As lgBox2DRevoluteJointDef - This has been moved the Globals so I can enable the motor in the LG_Update sub
   
    jd.bodyA = groundBody
    jd.bodyB = body
    jd.localAnchorA.set(0, 10)
    jd.localAnchorB.set(0, 0)
    jd.referenceAngle = 0
    jd.motorSpeed = 0 '0.5 * cPI
    jd.maxMotorTorque = 1e8
    'jd.enableMotor = True if this is uncommented then the body rotates immediately
    jd.enableMotor=False
   
    World.CreateJoint(jd)

and I have the sub

Sub LG_TouchDown(ScreenX As Int, ScreenY As Int, Pointer As Int) As Boolean
 
Log(ScreenX)
rotatebod=True
Log(rotatebod)
 
End Sub

When the screen is touched, the rotatebod is set true and the code below in LG_Update is used to enable the motor

Log(rotatebod)
    If rotatebod=True Then
    jd.motorSpeed=0.5 * cPI
    Else
    jd.motorSpeed=0
    End If

however, nothing happens as the body remains stationary. Can anyone suggest what I'm missing? I know the LG_TouchDown is firing correctly because of the logs. Thanks