This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
The problem is that PC sticks do not have the required resistance range. (They top out around 100k Ohms; whereas, A2 sticks top out at 150k.) As a result, the emulator will not detect a value indicating extreme Down or Right. One fix is to go to the PC Control Panel, select "Gaming Options" (or whatever it's called), and re-calibrate your joystick. The trick is to under- calibrate. So, when, told to move the stick in a circle, do not go out as far as you can. Instead, move it in a small circle. A different fix is to modify your PC joystick to increase its range. Adding a 0.01uF capacitor from each pot's non-ground tab to ground will do this. Running the leads through a small DPST switch mounted in the joystick lets you switch out the caps for regular PC use. (For details see R033EMUJSMOD.GIF.) Since the joystick's range is extended by flipping the switch to connect the caps, there is never any need to under-calibrate when in the PC Control Panel. Either way, to check and fine-tune your stick for emulator use, run an Apple II joystick adjustment program on the emulator. (See Q&A 030 above.) If you do the joystick modification, set the switch OFF, to the PC position, when doing any PC Control Panel calibrations. (Doing a calibration with the caps switched ON would defeat the range-extending function of the modification.) Set the switch ON, to the Apple II position, when checking and fine-tuning joystick adjustments on your Apple II emulator and for playing Apple II games on the emulator. By: Delfs and Rubywand Related FAQs Resource: R033EMUJSMOD.GIF (gif pic file)