JTA (Japan Transocean Airways) also has had big problem with maintainance not so long a go because of using parts that should not be used.
JCAB discovered these problems on routine check of JTA.
Also some JTA crew does not reporting engine over temps.
JTA is JAL B737 operator subsidary, base in Okinawa.
Okinawa is major maintainance base for JAL 737.