The paper studies the unbalanced magnetic force due to rotor eccentricity in permanent magnet machines. An analytical technique is presented for predicting the magnetic field distribution in a non-uniform airgap and the resulting unbalanced magnetic pull caused by eccentricities. The method is based on a simple modification of a 2D analytical technique for the prediction of airgap magnetic field distribution in surface-mounted permanent magnet machines with no eccentricity. Predictions from the analytical model are compared to 2D/3D finite element analysis. A test set-up is designed and built and measurement results are presented to validate both the analytical and finite element results.