Need Help!- Mach3 cutting undersize

[Hauntfreaks]

Hi... Ive had my cnc router running fine for about a month... I notice the other day a part I cut a few .125 holes for 4-40 screws to go threw... when they were done... the holes were to small.... then today i needed to put a slot in a part... and again it was undersized... I checked my stepper calibration and its dead on.... so I did a test cut... .1x.1 inside dia. square hole, once again undersized came out .085 x .085..... I'm lost .... any help would be great.... heres the G-Code

( test )
( File created: Wednesday, August 24, 2011 - 01:03 AM)
( for Mach2/3 )
( Material Size)
( X= 0.500, Y= 0.500, Z= 0.063)
()
(Toolpaths used in this file
(Profile 5)
(Tools used in this file: )
(1 = End Mill 3/64)
N100G00G20G17G90G40G49G80
N110G70G91.1
N120T1M06
N130 (End Mill 3/64)
N140G00G43Z0.8000H1
N150S25000M03
N160(Toolpath:- Profile 5)
N170()
N180G94
N190X0.0000Y0.0000F30.0
N200G00X-0.0266Y-0.0266Z0.2000
N210G00Z0.1000
N220G1Z-0.0720F20.0
N230G1X0.0266F30.0
N240G1Y0.0266
N250G1X-0.0266
N260G1Y-0.0266
N270G00Z0.2000
N280G00Z0.8000
N290G00X0.0000Y0.0000
N300M09
N310M30
%

[ger21]

Probably bit deflection or machine flex.
Try cutting the same size cutout in the opposite direction, and see what size it is?

[Hauntfreaks]

Gerry.... I think your right... I grabbed a hold of the Z axis stepper rocked it back and forth.... you can see in the video below the result .... I dont understand why only a few weeks ago it was cutting fine.... now to figure out how to fix the problem....

2011 08 24 16 11 24 426 - YouTube

2011 08 24 16 11 24 426 - YouTube

[Hauntfreaks]

looked deeper into this .... looks like i might have a bad linear bearing on the Y axis.... how would that happen??