You could also try the rapid IMU realign procedure:
Maneuver to 0,0,0 on the GDC FDAI
V41N20E, E,E,E (coarse align to 0,0,0)
V40N20E (fine align; NO ATT lt off)
76E, 40000E, 1E (set DRIFT flag)
77E, 10000E, 1E (set REFSMMAT flag)
Do a P52 option 3 (Note that auto optics may be off...