When you fit your new bearings stick them in a zip lock bag and put them in your fridge for an hour. The bag keeps them dry. It also helps dramatically to warm up the hub with a heat gun. Fit the disc side first, this is the fixed bearing retained by a circling. The other side is designed to float and is the centre of your problem when you try and drive this bearing home. It is designed to have a small amount of axial clearance. After heating the hub and cooling the bearings when you then fit the bearings they will go into the hub much easier and you will have some feel as to how far to tap them in until the inner race of the bearing contacts the spacer tube. Never push or strike the inner race as you will brinell the bearing and it will fail. The bearings you have driven in and locked up will be stuffed so toss them out. Fit the spacers after you have fitted the bearings (not before). Hope this helps.