I guess the last resort is to destroy the mechanism until it comes open - using whatever tool you can squeeze in there: Hacksaw blade, file, hammer/chisel, bolt-cutters, dremel, etc. You're going to need a new one anyway.
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Subaru ECU and TCU Website
1992 Alcyone SVX Version L
1992 Alcyone SVX Version L
1994 Alcyone SVX S40-II
2004 Subaru Legacy 2.5 SE Sports Tourer
1996 Subaru Legacy 2.2 GX Wagon
1988 Subaru Justy J12 SL-II