Sorry for the delay. I've been out of the office and answering what I can in the evenings. No excuses though. I apologize.
The first thing you do is get a replacement housing with bearings. We no longer service the bearings alone for many reasons.
Next you remove the top nut. If you have the cast iron deck pulleys you can try a pulley puller which is often your best bet on these older machines due to the type of key used in the shaft.
If you have the "split steel" pulleys use a hammer and brass punch to drive the spindle shaft out of the pulley and bearings. This is easier said than done. Often it requires on putting the nut partially back onto the shaft and smacking it with a hammer to break the shaft loose. Once the shaft is out you simply bolt on the new housing, slide the shaft in place, install the pulley and torque the top nut to 80-90 ft. lbs.