Vacuums: new choices, new problems.

Sweepers, stick vacuums, hand vacs, and even $1,500-plus robotic models try to compete with conventional upright and canister vacuums. But our latest tests show that some new vacuum choices and a record number of familiar ones aren't doing their job.

Six of 19 newly tested upright and canister vacuums broke or emitted high levels of dust, four of them consistently enough to be judged Not Recommended. Here are the dirty details:

Two out of three samples of the Dirt Devil Dynamite and Hoover Tempo Widepath (bagless) uprights, and all three Hoover Fusion uprights spewed an unusually high amount of the dust back into the air. Dust emissions are a concern especially for those with respiratory problems. The Hoover Duros canister's flaws included a plastic bag retainer that broke on one unit and a plastic bag lock that broke on two units. Those flaws caused dust to leak out.The Duros' tools also fell off the machine during vacuuming.

Those problems come amid challenging times for vacuum makers. Among higher-priced models, Dyson's bagless vacuums and its imitators are grabbing market share from established U.S. brands such as Hoover. Indeed, Dyson and Maytag, which makes Hoover vacuums, are suing each other in federal court over design and advertising claims. Dyson and Oreck are also suing each other in federal court over ad claims. At the lower end of the price spectrum, American brands face an onslaught of less-expensive models priced well under $100 and have begun outsourcing their manufacturing to cut costs.

More low-priced cordless vacs and the gee-whiz appeal of robotic vacuums that rove on their own are other ways manufacturers are battling it out for sales. But as our carpet and floor tests of more than 75 vacuums reveal, better-performing uprights and canisters have little competition for all but the lightest-duty cleanup.

Cordless vacuums don't deep-clean. Several manufacturers tout lower-priced cordless stick vacuums and pricey robots as replacements for regular uprights. Those we tested were fine for surface cleaning. But even the best of them aren't designed to deep-clean carpets nearly as well as the average corded upright or canister, so we tested and rated these alternative vacs separately.

We also found that some cordless sweepers and vacuums aren't necessarily easier to push than full-sized vacs, despite being smaller and lighter. Short run time was another problem for these cordless machines:The average for sweepers was 30 minutes before their batteries needed a recharge. Hand and stick vacuums lost juice after just 15 minutes.