Not sure the dealer will help, i figured it out by reading the sensor as i was moving the chair.
Heres an example (of what mine did).
I would move my chair forward, then 8 inches from the steering it stopped, it wasnt fully forward. Sometimes when i pulled BACK on the seat button it went more forward, so at that point the controls had reversed.
The below numbers are likely wrong but gives you the reason behind whats going on…. The tester showed the seat position sensors was at 32000 (it counts up as it went forward) then at that point went from 32000 to -32000 so that button then did the reverse, pulling back went forward as the seat computer reached its "count" limit.
I guess they thought the amount of play they would have would be fine, however after 10 years of use it got out of spec. So moving the seat with the position sensor unplugged allow you to move the seat and it not count, then plug it in to make it count "down" to 0.
Thing is you only get about 300 counts for a full movement, so would take you hours to reset it. I am guessing its a disc with holes in it (a bad one at that), knowing GM just replaced the whole base of the seat it would have come with the motor, position sensor and computer, they wont be able to diagnose that kind of thing. I would think the Tech2 would do it, however did they have training on the seat counter? Would high think not, when they just replace the whole seat base when it played up.
The post with the picture is below (took me a while to find it)