Thanks for the tips

I cleaned out that area by scraping a large flat end screwdriver in their and now it's pretty flat.

When I cleaned out the filament hole, I ended up putting a little bevel on it. I hope it won't negatively affect it.

The filament moves pretty freely through both holes with just a small amount of resistance. Is that fine, or do I need to touch it up with something?

BTW. Given that I'm about to go to the time and expense of implementing dual extrusion, is their any benefit of changing over from 1.75mm to 3mm filament?

Great community - appreciate all of the help