ill put the facts up here and the story below so if you don't like to read or don't enjoy laughing at those who do not know what they are doing you can skip the bottom.
ive attached a crude drawing of the part and i want to mill the "u-turn" rounded tip. the code has the .219 tool offset dimensions since G42 i cant make work either. from what i understand the line should read,
G02 X1.812 (where i want to end up on the x plane) Y-0.938 (where i want to end up on the y plane) I0.0 (no change in the x plane) J-0.187 (the incremental radius center on the y plane)

current g-code
%
O01230
(X-0 Y-0 MACHINE SIDE LEFT CORNER)
(MACHINE RUNNING IN ABSOLUTE INCH COORDINATES)
N005 G40 G54 G80 G17 G90 G20 G94
(TOOL#3 7/16 2 FLUTE END MIL)
N010 G0 X-0.250Y0.250 Z0.500
N015 T3 S1800 M3
N016 G01 Y-0.125
N020 G01 Z-0.020 F15
N026 G01 X1.812 F25
N030 G02 X1.812 Y-0.938 I0.0 J-0.187
N035 G01 Y-0.938 X-0.250
M03
%

so i have been attempting this for awhile now and have a TMC1000 bench top mill, it was originally dos and i got a copy of the windows 95 program that came with the later models. I have a full size mill and have in cases like this given up on the little CNC since i can cut the part at full 0.500 depth and round the end with a file, which is so far faster and easier since i could have made 50 of them with the time i spent on the gcode. i am not sure if i am doing something wrong in the code or the machine just does not understand it. right now if i cannot program and use it i may as well just sell it. i tried G42 comp and it never works out correctly, in the tool library it is tool 3 and D3 in the code. the tool diameter is set at 7/16 0.437 and the comp if set to 1/2 like the graphic in the program shows ti just follows the toolpath with no offset, if you set it to full diameter it cuts the tool diameter plus the coordinate. the cutter is cutting clockwise around the part so it should be the right hand offset from what i have read.

anyone that can fix the code if it is wrong i would appreciate it.