Anybody have any ideas?

Ohm out the windings. Figure out which ones are center taps for the
secondary or input voltage selects on the primary. (It may have two
independent secondary and/or primary windings if center-tapped out and
intended to work on both 120 and 240 VAC).

The lowest resistance winding is the high-current secondary. The
primary must be one of the other windings (if you're lucky the only
other winding is the primary!)

Tim.