Some teething problems I think, seems to be Z axis...?

I'm using Cambam but only really want to draw on the MDF bed of the machine at this stage. I've defined my stock as 5mm thick but the arcs lines etc are set to profile to only -1mm in the cambam dialogue. The G Code for the test is below, the machine homes just fine. when I Jog the machine I see Z- going in the direction of the bed. So I get a post-it and manually jog the Z until it bites the paper and then back it off say 0.650 mm and then set Z to 0 in mach. The theory being that the -1mm "cut depth" will push the biro into the mdf bed.

However when the program runs the pen seems to move up not the 1mm down I want it to go. I did some googling and changed the Z motor direction in Mach and that didnt feel at all right, homing went backwards (expected really). So my question, should I have selected a + z move (cut depth) in Cambam or is there a clue in the G Code below that the machine is set up wrong? Advice as always welcome. Thanks.

( Made using CamBam - http://www.cambam.co.uk )
( CNC_Template 9/3/2014 10:17:13 PM )
( T6 : 6.0 )
( CUTVIEWER )
( FROM/0,0,5 )
( Select dummy tool to avoid warnings )
( TOOL/MILL,1,0,20.0,0 )
( STOCK/BLOCK,500.0,500.0,5.0,0.0,0.0,5.0 )
G21 G90 G91.1 G64 G40
G0 Z3.0
( T6 : 6.0 )
( Tool Taper coming soon )
( TOOL/MILL,6.0,0.0,0.0,0 )
T6 M6
( Profile1 )
G17
M3 S1000
G0 X207.0 Y120.0
G0 Z0.2
G1 F300.0 Z0.0
G2 F1500.0 X196.5 Y113.9378 Z-0.1667 I-7.0 J0.0
G2 Y126.0622 Z-0.3333 I3.5 J6.0622
G2 X207.0 Y120.0 Z-0.5 I3.5 J-6.0622
G2 X196.5 Y113.9378 Z-0.6667 I-7.0 J0.0
G2 Y126.0622 Z-0.8333 I3.5 J6.0622
G2 X207.0 Y120.0 Z-1.0 I3.5 J-6.0622
G2 X196.5 Y113.9378 I-7.0 J0.0
G2 Y126.0622 I3.5 J6.0622
G2 X207.0 Y120.0 I3.5 J-6.0622