The M6, to hold the brake levers, I put down
to 9, not having an official reading what it
should be.

Still no luck finding the exact manual for the
BL-M425, but I found one for BL-M445 [1].
There, the correct torque is 6-8Nm. It also has
M6s so it is probably the same. Because I first
put it to 10, that's a 25% over torque at best,
so it'll be interesting to see what happens.

[1] http://si.shimano.com/pdfs/si/SI-8J50A-002-ENG.pdf

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