"Pull moves" for rectangular lattice polymer models are not fully   reversible
  "Pull moves" is a popular move set for lattice polymer model simulations. We show that the proof given for its reversibility earlier is flawed, and some moves are irreversible, which leads to biases in the parameters estimated from the simulations. We show how to make the move set fully reversible. 
D\'aniel Gy\"orffy, P\'eter Z\'avodszky and Andr\'as Szil\'agyi
q-bio.BM cond-mat.soft physics.comp-ph