OK.... Who's got a set of Rocket Tubes that don't work too well? Here's a fix.
The first thing to do is to soup up the blower. Even a good one seems incapable of propelling anything at 'blazing speeds' and legend has it that Marty Abrams used a vacuum cleaner in the commercials. The set comes with a Chinese motor and 15v powerpack. The motor is pretty sturdy and will probably take up to 20v. I'm using an 18v power pack and have had no problems. But first you have to fix the motor housing to enable the motor to cool down. The way the set comes, with the motor stuck in its little grey coffin, the blower almost seems designed to cause total meltdown. (My set hadn't been used much but the motor wires had melted right into the plastic.) Open up the blower and drill a hole (5 - 7mm) through the white casing on either side of where the grey motor housing fits on. (You shouldn't be able to see the holes when you fit the blower back together.) This creates a pressure differential when in operation, drawing air across the motor which will cool it down .
That was the hard bit. Next you have to reduce friction in the tubes to make them as slippy as possible. Take them apart and buff them up with some furniture polish. Even if you don't use the tubes this will make them look a whole lot better.
Finally, check for air leaks. Obvious and tedious but worth it. Use some invisible tape at the joins and save any really bent tubes for the vertical part of the set.
Try this at your own risk! All I can say is it worked for me. I know they're not everyone's bag, but l like the Rocket Tubes. (I'm sure they used them for the city in Logan's Run.) They show a kind of naiive optimism about the future, which appeals to me. Especially since the future is much more likely to involve a bunch of Americans shooting each other over the last gallon of petrol... ;- p