I overhauled the actuators on a '57 model recently, it is a lot of work as the whole tail assy must be removed. The problem with these is the assemblies cannot easily be accessed for lubrication, as there is a boot cover protecting the screw jacks. The bearings can be had from Cessna for around $36 each, These were the problem with this airplane, as the trim was difficult at best to adjust. I replaced all of the hardware on the tail assy because I could. When removing the actuators, it is vital that attention is paid to the measurements of the actuators as they must both be the same dimension to prevent the stab from binding. Total for the bearings and tail hardware was around $100, the labor to do this is around 12 hours. Hope this helps, any other questions let me know...
-Tom