I had some difficulties installing my own Phil Wood BB recently...no matter how well I thought I'd cleaned the threads, and even using a pretty generous amount of the blue thread locker that they include - the damned cups kept backing out after a few hours of use. When I asked the owner of my favorite bike shop about my problem - he gave me some of his "Loctite Primer" to use, and Voila - everything is fine now and I love my new bottom bracket. BTW, it comes in a spray too

https://www.amazon.com/Loctite-19269.../dp/B00FKFGSHE