Taz 4/5 has issues with Z Home

My Taz 4 (upgraded to 5) has problems with homing Z. When I tell it to home Z it makes a loud noise for about 60seconds and then moves. If I move the Z my giving commands for going up or down what ever amount I want everything is fine no noise immediate smooth movement, but hit home for Z and I get the problem again. It acts like its trying to turn the Z steppers but its not getting enough torque.

It seems like if it was the controller or stepper motor it should have an issue with the Z movement commands also. I have reloaded the failsafe firmware with no difference.

FIRMWARE_NAME:Marlin V1.0.0.1; Standard V2.0 FIRMWARE_URL:https://code.alephobjects.com/diffusion/MARLIN/ PROTOCOL_VERSION:1.0

My M503 shows
Send: M503
Recv: echo:Steps per unit:
Recv: echo: M92 X100.50 Y100.50 Z1600.00 E833.00 E1800.00
Recv: echo:Maximum feedrates (mm/s):
Recv: echo: M203 X800.00 Y800.00 Z8.00 E40.00
Recv: echo:Maximum Acceleration (mm/s2):
Recv: echo: M201 X9000 Y9000 Z100 E10000
Recv: echo:Acceleration: S=acceleration, T=retract acceleration
Recv: echo: M204 S500.00 T3000.00
Recv: echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum XY jerk (mm/s), Z=maximum Z jerk (mm/s), E=maximum E jerk (mm/s)
Recv: echo: M205 S0.00 T0.00 B20000 X8.00 Z0.40 E10.00
Recv: echo:Home offset (mm):
Recv: echo: M206 X0.00 Y0.00 Z0.00
Recv: echo:PID settings:
Recv: echo: M301 P16.91 I1.13 D63.45

After a lot of help with the lulzbot support guys here is the fix.

The Z Max speed limit had reset to 8 when I had powered the printer off. When set to 7 or less the problem is gone. I normally have in my print start scrips in all the slicers is M203 X192 Y208 Z3 which would have set the limit to 3. If I had not needed to re-zero my Z from changing the nozzle I would never had see the issues since it would have been set back to sane settings with the first print.