And for anyone finding this thread with similar problems, it looks like it was probably 1 of 2 things, or a combination of both;
- the broken fan
- the filament feed tube not being seated tightly against the nozzle, as I found a thin ring of cooked plastic inside the Bowden fitting.

either way, it’s fixed now and I’m able to once again get complete, reasonably good prints, especially after calibrating the paid head and filament feed.

thanks again for the helpful responses