I bought a press new for £99 to do the rear bearings on my focus, and it will help with all the jobs on my XR3i such as bushes and all the bearings etc etc, its a handy tool,
but as people say if ur just doing the bearings they do drift out, especially if you give them a good heating through, but obviosuly not enough to warp any drums etc etc
By the way not sure but can your bearings be adjusted, ie tightend up like the MK4 ESCORT, if so try giving them a tweak........