My Kenmore bagless intelliclean vacuum is making a loud noise mainly when it is vacuuming on the highest setting (when the light is red). We have taken it apart and cannot find a clog. It has also lost suction.

This might help, it was posted on a previous problem but is the same issue you are having it seems: "Here is a possible solution. If the vacuum sounds normal when the green light comes on, then the issue is a suction bypass. Kenmore built a suction bypass in to help cool down and protect the motor should someone either never clean the filter, empty the canister or somehow manage to clog the hose. There is a spring holding the bypass closed and is overridden by vacuum suction. I guess the spring becomes weak, allowing high suction to pull it open which in turn reduces suction so it closes again. It can do this several times per second making a loud racket and slightly affecting performance until the sensor goes green, then the vacuum suction is too low to overcome the spring tension thus why it sounds fine then. The trick? The very hard way (what I did) was to open the vacuum, open the casing where the spring is and pull it apart slightly to increase the spring tension. The easy way is to put tape over the hole where the bypass is. The inlet is under the hose track on the back on the right side as you're looking at it. The hole is about the size of a quarter and you'll see fins across the hole. The tape would keep the suction. The motor would still pull back the bypass but since tape is applied, there would be nothing to reduce the suction thus keeping performance and reducing the noise. However, this circumvents the intended design so you do so only at your own risk."