Recent experimental observations on the plastic deformation of icosahedral Al-Pd-Mn single quasicrystals are described originating from conventional transmission electron microscopy in a high-voltage electron microscope (HVEM), from in situ straining experiments in an HVEM and from the determination of activation parameters from macroscopic compression tests at low temperatures. The moving dislocations are created by multiplication events initiated by cross slip. They trail planar faults of different electron microscopy contrast. Since recovery occurs at high temperatures, the dislocation mobility should be discussed on the basis of low-temperature data. While it was previously interpreted in terms of an extended cluster friction model, the present paper shows that it can equivalently be explained by the Peierls mechanism on the cluster scale.