Robot failing to dock

When my robot (l20 ultra) goes back to the docking station, it lines up to back in then as it backs up it sort of... Drifts right, which puts it out of alignment to dock. It keeps trying to back in diagonally until it finally says it failed. Called support on this but the only thing there care to do is verify warranty (i.e. look for a reason not to help) so hoping the community might be able to.