let's hope that it's a temporary easy fix - if it is truly open all the way, with all corners out the same distance, then it doesn't sound like a column/gear issue, but one of a motor going 'bad', possibly - they can be replaced on the spot, but yes, the slide will have to be about 1/2 way in/out to get to it, and to get to the outside top motor 'set' screw.
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