How do I tweak B1900D autopilot?

I've got the 1900D (the one with the slightly modified FS King Air panel). The A/P snakes endlessly when capturing the localiser---even using a 20 degree intercept at the correct airspeed! (No problem with the glide.) I'm pretty clueless on the software side. Who can help me 'tune' the A/P localiser capture function? ThanksGWI [EGKA]PS: No such problem with the 1900C---except always having to bring the throttle quadrant up to change A/P functions. Otherwise, the 1900C is great!