I feed Aquamax 500 and 600 by hand, so I can't address mechanical feeding issues.
I do notice that the exact size of 600 pellets will vary from bag to bag (I only use 1, maybe 2 bags of 500 per year).
Quality on a lot of products has declined since the Wuhan Flu hit. Lance Cheese crackers have noticeably more peanut butter leaking out onto the packaging these days.