Well Done!!!

Have a good long celebratory drink, you deserve it.

Your write-up/explanation will be invaluable as our FL2s get older and in need.

(Don't forget to add 'RESOLVED', or similar, to your Thread Title, Thanks) FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 82k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Well done.
As you had the air filter box out did you check that the drain washer was present?

No I didn't know about that but is was bone dry inside.

I'll check it next weekend.

Thanks for the heads up.