I disassembled a Seiko 5139A today and discovered oil—and it is green. The entire movement down to the bare plate was covered in oil. No wonder the amplitude was almost nothing and the Balance was straining to move.
Hi on these plastic/welded movements I use Carburetter cleaner in a spray can and dry under a light bulb on tissue the carb cleaner dries with no residue ok,Then spin up on a line release unit to free up everything. it works on some others NBG so into the scrap box.