Rebuilding a shock...doable at home?

These are 'soft', can compress them and extend them by hand 6" in about 2 seconds each way. Would you wanna sell or buy a soft shock? The oil is saved in a bottle an one is untouched. I have some new shocks and I can barely compress them an inch a second. Perhaps these valves are shot. I have not really checked them out, just observed there is one O-ring in this model.