Decided to put the sensor into spec since its clearly not clocked 60 deg per the manual (another case of BITOG ocd). First off, there is no way it was only torqued to 24 nm. Holy [censored], was afraid the bolt was going to twist off, it was refusing to budge, it was really battened down. When it did break loose it emitted a nasty fingernails on the chalkboard screech. Youch. No joy w/ std ratchet had to use an 18" to get enough leverage. On a knock sensor. Wow. After inspection to make sure the bolt was still intact, went ahead and clocked to 60 deg and re-torqued @ 24 nm.
The factory service manual makes no mention of using any thread locker and where it sits doesn't get wet so it almost seems it might have been seriously over torqued at birth. Not generally optimal for a knock sensor to be over torqued, glad I investigated this.