front brake master cyl. question

I was wondering if it's possible to rebuild the front brake master cyl.? I think a seal is leaking inside, since I slowly lose the stiffness and response in the lever, until it's all the way to the throttle bar. Then, if I bleed the master cyl., it's fine again....for a while, then the same thing happens. Is this common?
I know that a new one is about $220(!!!!), and I'm hoping to avoid spending that much. BTW, this is a 2001 750 SS.

I've had exactly the same thing on my 998.
The MC has been replaced under warranty (it allows them to discover that their demo S4R suffered from the same thing).
It appears a complete serial of PSC16 brembo are affected.
Someone told me a rebuild kit exists for it.
I'll try to have more info

I've just found that:
http://www.cyclebrakes.com/html/rebuild_kits.html
Call them, sure they will have for Brembo mc.

There's another solution: check Yamaha R1 spare parts: they use Brembo PR16 (radial) and in europe it's a lot cheaper than the ducatis brembo OEM parts.