Case Clearance
WARNING: This page is about a different car, the 2013 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.
Measure the clearance between outer rotor and oil pump case. If clearance exceeds the standard, replace the oil pump case.
Case clearance between outer rotor and pump case:
Standard
0.10 - 0.175 mm (0.0039 - 0.0069 in)