https://www.buymeacoffee.com/frobo64v

This video shows how to fix leaking problem on a M9000 brake lever, the problem is the piston inside, I am pretty sure most if not all shimano brake levers use the same piston, I am pretty sure this will work on m7000 m8000 and m785 series as well but I am not totally sure on the m7100 m8100 and m9100 series, they are the newest series and I cannot find info on the piston size but I imagine it should be the same

Getting to the piston is a little different with Shimano Servo Wave levers, here are a couple of links showing how to disassemble and reassemble them, they are not the clearest but they are the best I could find, will also link a short which has good picture quality of the inside

   • Shimano Deore XT M8000 Brake Lever Ma...  

   • Shimano XT M8000 Lever Overhaul  Com...  

   • When a SHIMANO Brake Lever is Disasse...  

Here are the links for the two different orings, first link choose 10x5x2.5mm , second link choose 9x5x2mm

They are from the same seller so you should save a little on shipping of buying both from them at same time in shopping cart


(10x5x2.5mm)
https://vi.aliexpress.com/item/100500...


(9x5x2mm)
https://www.aliexpress.com/item/10050...


Music Credit
Artist(s): Filo Starquez
Track: The Shack
   / @filostarquez  

Mineral Oil
Seals
Pads
Piston
Plunger
Clip
Bleed
DIY Do It Yourself
Guide
Air