You might try asking here, Flyte Tyme
Terry Lewis and Jimmy Jam have a forum set up.
I remember reading that they had Oberheim, Yamaha DX1 and DX/TX units, also lots of TR-808, they rarely sequenced anything, almost always played live to tape. Bass is usually Jimmy playing electric bass then adding a keyboard part on top of it. They used a lot of samplers in 1986 too. Could be a mix of layered synths.
This is newer video Madjef at Flyte Tyme studio in the 90s on Vimeo
jump in to the middle to see a tour of their studio in the 90's so many keyboards no telling from this video what all they have. They are just stacked up against the walls.