I would contact Melett in the UK. Your fix may be as simple as just replacing the center cartridge for the turbo. I bought from them when my K27 turbo blew on the e28 turbo. back then it was 485.00 for the cartridge. I pulled the turbo removed 12 10mm bolts swapped out the cartridge and it has been running ever since. http://www.melett.com/