SV06 PETG build-up on hotend. Why?

I keep getting a boatload of PETG build-up on my hotend. The early symptom is when I go to change filaments, I can’t get the new filament through. I heat up and clean the hotend and everything works fine for a few prints. Then I may get a bad portion of a layer, or an entire print may fail. When I check more buildup on the hotend. Now the entire hotend is encased in PETG. I have completely disassembled the printhead several times and I didn’t see anything suspicious.

Thoughts on what might be causing this problem? I’m getting ready to install an entirely new printhead and I don’t want a repeat of the problem if it is something I am doing that is the cause.

Thanks in advance