We have been looking into the P54 failures, and testing some new ideas to hopefully fix the problem in the near future. Unfortunately we've been very busy and getting results is taking longer than expected.
As a note we have never instructed customers to glue the forward closure in place, although it seems to help it doesn't always work. Sealing the forward closure to the liner causes the liner to take the pressure from the motor, the liners aren't designed to hold that much pressure. In fact the original design had no small oring between the closure and liner, so that the gasses from inside the liner could egress between the liner and forward closure. I still think this is the key to the problem, but we need to test some more to come to a conclusion.
Our thanks to the rocketry community for all their patience and support of our products.
Bob.