Will Dad be able to walk on his own again after his stroke?

Hi My dad had a stroke in December 2009. He has come a long way from being completely paralysed on one side and the doctors not really holding out much hope for movement ever again. He did 2 months fulltime in a rehabilitation centre and is now home. He walks for 25 minutes at a time around the local neighbourhood with someone holding his hand, several times a day, as well as riding an exercise bike for nearly an hour. He does little jobs around the house hanging onto his walking stick or walking frame - weed killing, cutting branches off trees, feeding pets, bringing in washing on his walker, etc. He would like to be able to walk on his own again but he says his left leg feels like lead and is very heavy when he walks and it sometimes gets stiff and stuck and he is frightened he will fall over if someone is not holding his hand. Do you have any suggestions for lightening up his leg? Thanks for any suggestions they are much appreciated. Cheers Sandra