After researching this issue I have a couple suggestions for cleaning the Therminator.
First of all I am convinced it is impossible to really clean the Therminator thoroughly due to the design of sealed plate chillers. Since the chiller can never be taken apart there will always be trapped particles in the plate system. I have run hot PBW, backwashed, baked in the oven, more PBW, more backwash and thought I had my Therminator reasonably clean. Was I wrong. I saw this new caustic cleaner called TM Desenamax at Williams Brewing. Cool cleaner that is purple when clean, blue when dirty, and yellow when very dirty. I ran two batches thru my Therminator and I was totally shocked all the debris that came out! I know Blichmann does not recommend caustic cleaners but this cleaner was fantastic.
Second, the only way to prevent reoccurrences is to prevent debris from entering the Therminator. I use the Beer3 hopback just before my Therminator with the concept it would act as a filter when filled with whole hops. The problem with this hopback is that the false bottom has 1/8 inch holes that allow too much whole hops to enter the Therminator. My solution to that problem was to place a 400 micron canister filter in the hopback. Mine came from Arbor Fabricating - Chad the owner/fabricator is awesome to work with and his products are the best quality.