Is there a known issue where the STT-8300M will auto guide with the main sensor but not the internal guiding sensor? CDD Ops used on Win 10 platform and mount calibrated for each sensor and success confirmed. With the small guiding sensor as the active sensor, the EM 400 Tak mount can be moved with tabs indicating that the main cable between Camera and Mount is OK. The smaller guiding sensor will also take an image hence me being baffled so its should auto guide on the auto selected star. Changing to the main sensor for guiding, no problem. At wits end. Would appreciate any ideas. Many thanks Richard - Tasmania.