I have not worked with the Hagie, but had the same problems with a Patriot 3185. 

• Do the dead zone calibrations.
• Then raise the deadzones 1-2 points higher than they calibrate.
• From there work with the steering gain to fine tune.  On some systems the steering gain can be very touchy and a quarter of a point will make a lot of difference.  Try tune the gain at the speeds the sprayer will normally run.