Sounds like you borrowed my roaster

I've owned a few of the smaller dedicated air coffee roasters and none of them hold up like the Westbend Poppery II. The lids do get ugly.
3 minutes is fast. If you did a pound in 4 batches you might reduce the amount of beans per batch. It takes at least 5 batches/lb for me at 4:45-5:15 per batch, first batch always the longest especially in cold weather. I like a Full City roast with minimal or no second crack. Zero oil. I've also found that different electric plugs in my house will roast differently, some slow, some fast. I finally found the one in my garage that gives me a consistent result.
I've not had great luck roasting dry processed beans. Sweet Maria's sent out a tutorial about the difference but it wasn't worth the effort for me especially using a popper.