Sent an email to Forge Motorsport enquiring whether it was possible to buy a service kit (seals, springs) for one of their blow-off valves. 2 days later a jiffy bag pops in through the post with said kit. free of charge!.
Top marks Peter Miles at Forge

 

I'll second that - Forge are really excellent to deal with

 

From my days of Renault 5 turbos i found them very helpful and generous!

Dave