Seat movement in 2018 GMC Yukon

I recently purchased a used 2018 Yukon Denali (4x4) w/ 43k miles. I have noticed a sound/sensation combination since shortly after taking possession of it. It is a slight “clunk” that reverberates through the seat and I both hear and feel it.

It FEELS like my seat track is moving 1/32" or 1/64" forwards or backwards each time I come to a stop or accelerate. It does not appear to be a lateral (side to side movement) as I do not notice it in turns.

I took it into the dealer and they installed some type of retaining clip that appears to be attached to the underside of the seat. I believe this is the GM version of the “hose-clamp” fix but it has not alleviated the problem at all. (And as I said, I did not notice any lateral movement before or after this was done ).

I was able to minimize the sensation by immobilizing one of the seat motors (which had some play in it) using a zip tie. The sensation of movement (or clunking) on the right side of the seat (closest to the center console)has gone away but the left side click/clunk seems to remain. I cannot find any lost parts or components under the seat though if I grab the seat as a whole and try to move it forwards and backwards on its track there is SLIGHT play and a similar sound (though it’s quieter).

I tried to do the same thing with the passenger seat (also powered and heated/ventilated) but it has no play/slop/movement at all and I have sat in it while driving and have not felt it at all.

I have addressed the issue with the dealer but they seem to just be guessing at this point and although I have an extended warranty (the vehicle has 43k miles on it) it is a pain to use and it causes me to be without a vehicle for a day at a time usually.

I have searched and searched online and cannot seem to find mention of this specific issue except on the previous generation Tahoe/Yukons and those instances seem to involve much greater amounts of seat movement (1/4"-1/2").

Does anyone have a suggestion as to how to fix this issue? Perhaps a shim or a retention screw tightening, or any bulletin or other known issue that could help me ID exactly what’s going on? (I’ve driven other similar vehicles of similar age and have never noticed this problem before and if I don’t have to live with it I’d rather not especially while I have SOME kind of warranty in place).

Any help would be much appreciated.

Thank you in advance.

Is it possible it has a memory function for seat positions? If so can you turn it off and see if it does not happen? Sorry you will probably have to refer to the manual for that info.

Well perhaps it’s possible but Im not sure how (nor am I certain that it is possible to deactivate the memory as it only moves the seat when a button is pressed). The movement is very slight but it happens during nearly each acceleration and deceleration almost as if there is some free play in the seat track.

What do you think?