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You can use a flash upgradeable hand control with  SkyAlign technology for your older NexStar GT or GTL scope. (These telescopes are identifiable by the tube ring clamp that holds the telescope tube to the fork arm.)

Celestron no longer sells the NexStar hand control. The current (early 2012) version of the newer NexStar+ hand control won't work with this old mount design. Check the aftermarket and classified ads on astronomy sites such as cloudynights.com for used NexStar hand controls.

Then reflash the hand control to the GT 4.03 firmware per these instructions:
http://www.celestron.com/c3/support3/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=1747&nav=0,255