I have the Rainbow Astro RST 400 which uses the same ascom driver as the RST 135. My RST 400 has a guiding issue still today. The star is driven right off the screen and can not be tracked. Additional when I stop guiding the mount just keeps on going. I have to bring up the joystick control and hit the stop command to keep it from continuing on. I tried reducing the guide rate, and the pulse duration for calibration no change. Any help please... Bruce

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