Check the following on your selector.

- worn tape guides

- fold down the selector board and look at the magnetic sensors. specifically the level up / level down ( i think they call them stu / std ). if they are loose, your leveling zone may be too tight and will have a hard time leveling into the floor

- if the top floor is more of an issue than the others, you may need to look at the magnets on the tape, make sure they are glued / placed correctly. typically a paper or plastic jig is left on the cartop or machine room after install to help you determine spacing. also i believe the back page or two of the prints should show proper selector installation.

are all of the floors roughly the same travel or is the top floor a short floor? leveling speed is somewhere in the 4-8 fpm range?