My bike's Dura-Ace R9120 rear-brake/front derailleur shifter (left shifter in UK) leaks brake fluid when I pull hard on the lever. It leaks from this specific place:
I understand this lever is mechanically identical to Ultegra R8020, and have found a couple of forum posts on other sites covering people's fixes, but these levers either leak from a different location, or the fix doesn't work e.g.
I have replaced the diaphragm and re-bled the brakes (this part: https://www.sjscycles.co.uk/gear-spares/shimano-duraace-str9120-lid-unit-left-y0c598030/). The lever is firm and works well, but if I pull hard on the lever it leaks.
Is this lever repairable?