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Calipers and brake levers? More out of curiosity than anything, to see where bubbles may lurk
what we need is the shimano version of this SRAM cutaway
(forum wont let me actully interact with the image pop-up box, so this below is a blind guess:

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Exactly
If you don't find anything useful, I've got a M6120 caliper in the garage with a cracked piston. I can split it in half and take some piccies tomorrow if you want?
Not sure if I've still got the knackered levers or not. Might have binned them.
If you're struggling to get a good bleed, might be worth looking into replacing the bladder in the lever?
Shimano actually published such a diagram a few years ago when they redesigned the caliper internals to allow a more "straight through" oil bleed. Can't say I've seen one of the lever end though.
@scoitroutes that was in my mind when I posted this but I can't remember where I saw it either.
I'm interested to see where the oil flows ?
@scoitroutes that was in my mind when I posted this but I can't remember where I saw it either.
I'm interested to see where the oil flows ?
@scoitroutes that was in my mind when I posted this but I can't remember where I saw it either.
I'm interested to see where the oil flows ?
That's the badger - thank you
Need one for the levers now lol

All I can find for the levers is an exploded diagram although I think things are fairly straightforward. In terms of the route the oil takes it looks like you just pull the lever to apply pressure to the reservoir at one end & the oil exits opposite.
The icon for one way bleeding makes more sense than the implementation

if they apply the same to the 4-pot, then this is where I figure those bubbles get caught particularly in the rear caliper

