Thanks for the discussion all. I had reoccurring clogs with my CR-30. All seems well now as I’m printing a quality part again, which happened after reading this thread. My issue seems to have been caused by what you call heat creep: I had the PLA stand melting in the Bowden tube, too far upstream from where melting should be happening. Before I got this problem, I had just completed an 8 day print (11 foot long part), which came out perfect. Then clogging all the time.
I don’t know why I suddenly had the problem and I don’t know why it shouldn’t happen again.
The upgraded blue tube I installed was junk now, with PLA stuck to the inside diameter like plaque in an artery. I installed the original white PTFE tube and all is well. One clue that this is happening to you is if you cant remove the bowden tube from the connector at the heater block (after pulling the strand) with the release ring pressed. It wont come out if the thing is cemented in with melted PLA.