Steer and gear in Columbus rebuilds both manual and power boxes, try them for a rebuild kit. Better yet, send them yours and they can rebuild it, but of course for a fee. Power boxes are kinda complicated - Ive looked at tearing one down before but decided to send it to steer and gear instead, they will warantee the work as well.
On the grease - that was probably just sloppiness by the factory or a PO getting messy. My guess would be white lithium should be fine.