Weeping front brake master cylinder

2010 GSA ABS, I appear to have a weeping front brake master cylinder, I can see fluid on the banjo which appears to be coming from where the reservoir attaches to the unit, does anyone know if I can buy a seal kit? Do I just bleed via the front callipers? Any advice welcome, thanks

Just bleed it as normal ( non ABS) system.
Someone will be along to say where to get a seal kit from, I don`t think BMW sell them.

The reservoir seal (o ring) was around £2.00 from Motoworks, removed cap/sponge etc and removed handlebar clamp bolts...emptied brake fluid...2 bolts holding reservoir undone, emptied brake fluid, removed reservoir and replaced seal, replaced all the bits, clamped back up, fill up reservoir.......job done in 20 minutes thanks G5RJO