Cleaning an EGR

[VW1300]

Has anyone taken off and cleaned the EGR, especially on a 606? I did the EGR bypass but still am getting a P0400. The first time the code reappeared after the bypass, I changed my little air filter on the bypass and the code went away, and mileage increased again. Now 4 months on, this summer, mileage has been dropping again and finally the P0400 came back. The EGR appears to be opening and closing, I'm wondering if it's so sooted up that even air from the bypass can't get through very well. The flaps appear to be working properly.

It appears the EGR just unbolts, and cleaning should be straightforward I think. Just wondering if someone's been there/done that.

Thanks,