I noticed that a small amount of mineral oil had leaked from the bleed port on my Shimano road brake lever. I inspected the bleed port screw and saw that it was loose. The threads on the lever appeared to be damaged. The threads on the bolt ("Y0C698030") appear to be fine.
I was able to screw the bolt back in, pumped the lever a few times and it seemed to stay put. No further mineral oil leaked and the braking does not feel spongy.
However, now I'm not sure what to do:
- Is the brake safe to use?
- Can I repair the thread, perhaps with a helicoil or threaded insert? If so, what are the dimensions?
- Do I need to replace the entire shifter?
- Should I make a warranty claim with Shimano?
Here is the brake/shifter diagram for clarity: