Pass Over Reference Z Axis

Hi Everyone,

Can anyone help, I have a Bridgeport Interact 1 Mk2 with Tnc 151 A control.

My problem: Switched the machine on this morning everything fine up to the first reference move (Z axis), Will not reference in Z.

The spindle moves upwards until it hits the limit switch at this point extinguishes the power enabled light, I opened the front panel that the Z joystick is on
and held the left hand micro switch in pressed the power enabled button and then the cycle start this the allowed me to drive the spindle downwards as much as I required but would still not reference in Z as soon as I let go of the micro switch the spindle would move upwards and hit the limit switch?

I changed the order the machine references in parameter 59 to "6" (X-Y-Z) and X-Y axis referenced ok but the Z axis did not?.

I have checked the encoder on the spindle I think this is ok (light is on and I am getting an analog signal at the Tnc control.

The spindle is not on the hard or soft limits before I reference, I have the habit of driving the spindle downwards at least 30mm before I shutdown the mc,

Thanks for any help, Allen.