Greetings;

Great questions above, I have a few more.

Does your material have enough resonance time in the dryer hopper? The material needs to have 4 hrs of dry time in the hopper.
What is your hourly throughput of material?
What is the size of your hopper?
If your 4 hour throughput exceeds your hopper size , that could be an issue.

Have you checked your dewpoint, with a stand alone device, lately?
Does your process start up fine the start drooling after a few hours?

Thanks

Scott