You are right, product and operator are key, but it doesnt take a rocket scientist =), and just good mulch not nasty large chunky trash which we would never put down. What unit did you have? The old air locks are inferior to current models, and about half the size. My guys LOVE that shoot, they can trim along window sills, garden beds, and direct mulch where ever they want it just by turning the nozzle. The airlock is about 20k, we currently have 2500 hours on ours, and still have a lot of life in it. All depends on what you run through it. We have hardly any scratches in the drum, and you will be lucky to fit a piece of paper between the drum and the wheel. We run only great stuff through it though. Sorry to hear it didn't work out with yours.