HMC Program Trouble with G03

Im having trouble with the arc motion on a G03 move. I have a feeling the machine doesn't think the geometry matches up within .001, but I have double and triple checked my math. I have also played around with the values of x and z to see if I can find the difference in logic between me and the machine, but it must be greater than .001 because I incremented x and z by .0001 ten times both positive and negatively and simulated it each time and go the same error.
Here is the program;
%
O51712(PRESSURE BLOCK)
(MATERIAL -YELLOW BRONZE)
(ORIGIN-X,Y,Z ORIGIN CENTER OF STOCK RADIUS MINUS .150 CLEANUP)
(TOOLS)
(TOOL - .200 SQUARE GROOVE TOOL)
(TOOL -55 DEG)
G18 G20 G40 G80 G90 G99
G00 G28
(55 DEG-FACE AND TURN)
T101
G50 S150
G96 S60 M03
G00 X18.5
Z1.0
G01 Z.250 F.05 M08
G71 P001 Q002 D.05 U.05 W.05 F.005
N001 G01 X0.0 Z0.0
N101 G03 X16.5 Z-.943 K-42.0
N102 G01 X16.5 Z-1.125
N103 G02 X16.75 Z-1.125 I .125
N104 G01 X17.00 Z-1.125
N002 G01 X17.0 Z-3.0
G01 X18. Z-2.0 F.05
M05
M09
G00 G28
M00
;;
The error occors on N101, but only when it takes the finishing pass of the G71 canned cycle.
So the simulation will run through the entirety of the roughing passes that it calculates from the profile specified between the P and Q blocks, and in essence creates the proper shape of the part. Then as it goes to take a finishing pass it alarms out with an invalid I, J or K in G03. I have had this issue before on smaller parts and was able to play with the numbers until I found values the machine would accept, but that is not working for me this time. This is for a Haas ST35-Y.

Switch to radius mode: it solves a lot of problems.

Cheers
Roger

Your error could be that both I & K need to be stated on all arcs

N103 would also error as it would use the K-42. value from line N101

Suggest that all arcs have both addresses stated, and they are modal

without a print or geometry It's hard to help. from what I see the math is wrong.
try this code and see if it works for you.

O51712(PRESSURE BLOCK)
(MATERIAL -YELLOW BRONZE)
(ORIGIN-X,Y,Z ORIGIN CENTER OF STOCK RADIUS MINUS .150 CLEANUP)
(TOOLS)
(TOOL - .200 SQUARE GROOVE TOOL)
(TOOL -55 DEG)
G18 G20 G40 G80 G90 G99
G00 G28
(55 DEG-FACE AND TURN)
T101
G50 S150
G96 S60 M03
G00 X18.5 Z.250
G71 P1 Q2 D.05 U.05 W.05 F.005
N1 G0 X0.0
G1 Z0.0 F.005
G03 X16.5 Z-.81824 K-42.0 (-.8182 CORRECT VALUE FOR END OF ARC @ X16.5)
G01 X16.5 Z-1.125
G02 X16.75 Z-1.125 I.0625 ( I.0625 CORRECT FOR X16.5 TO X16.75 DIA.)
G01 X17.00 Z-1.125
G01 X17.0 Z-3.0
N2 G1 X18.5
G0 X18.5 Z.25
M00