I'm pretty sure you have to drop quill, then loosen bolts around the top bearing (see 1 bolt in first pic left edge of pic), if your lucky that bearing will lift out easily, if not, I typically use a bearing separator to grab that groove and tap it out. I seem to remember there is someone supplying parts for WT, but cannot remember who, other source would be ebay for a used unit. I know I contemplated replacing a pulley some years ago, cannot remember if it could be done with a new off the shelf pulley, would need custom bore, then use the old (or make new) brass spline pieces. I know I looked at that route, cannot remember if it was possible.
