Rear brake piston

[gently-does-it]

Hi all,
Ive generally found all my answers by trawling this amazingly informative website but not this time.....

So here's my problem. Today I stripped the rear brakes on my 2002 1150 GSA and the piston ends are not round, they seem to be worn around the edges and in the process of examining them I managed to knock a little hole in the bakelite brittle material that makes up the face of these pistons.
So, can I get a kit to replace these pistons or do I even need to? And if I do have to get the parts can anyone recommend a supplier?

I've attached some pictures which I hope will make things a little clearer for all you nice people who are going to try to help me.

Thanks in advance.

 

[slimbo]

dont panic they will still work , i did similar to mine a couple of years ago and nowt has happend.

 

[gently-does-it]

dont panic they will still work , i did similar to mine a couple of years ago and nowt has happend.

Nice one Slimbo, thanks.
That bakelite stuff is about as brittle as my bike maintenance confidence.