found this post on a duke forum
http://madoegy.blogspot.co.uk/2009/11/sticking-piston-due-to-dust-seal-in.html
could be worth a go.
john
Bluddy 'ell clicked on that and got loads of pop-ups
sorry mike i didn’t have any probs
john
Anyway not in the same class, again, but the old P8’s you rebuild (if you rebuild) with lots of the special red grease under the dust seals. Must be a reason
finally stopped the disc getting to hot, spent several hours working the pistons in and out with some gt85 for lubrication, can now push them back with my fingers ,will have to keep an eye on the situation though.
john
Well done, and, probably.
Mine were the early plain steel pistons, which rust, (Spada same) best bet was (in both cases I’m pretty sure) replace with the teflon coated versions, eradicates the seizing up probs.