Kadee! A name associated with the best and the worst in coupling! Unfortunately, the Kadees are the best couplers around so we have to put up with their faults.....AND THEY HAVE MANY!
But Jim-d is right! The Kadee coupler height gauge and the pliers that adjust the uncoupling levers are both a must if you intend to keep your levers on, but other factors enter into the equation as well and should be considered before you start snipping your levers off. The first of these can be corrected by the average modeler, the other, unfortunately, cannot.
First, you must check the level of your track. Any abrupt rise or depression in one or both of the rails can cause an unwanted uncoupling or, worse, a derailment. This can happen when the uncoupling lever hangs down far enough to touch a rail, and this almost always occurs on a turnout or crossing where one or more rails pass directly under the coupler. Adjusting the uncoupling lever with the Kadee coupler height gauge and adjustment pliers can usually keep the levers far enough above the top of the rails to prevent this from happening.
The second problem is one we cannot fix on our own. This has to do with the excessive vertical play inherent inside the Kadee #5 coupler box. Whoever designed this box should be excommunicated to Siberia, or worse, since it allows the coupler to move up-and-down much more than necessary for the couplers to couple, track and uncouple properly. The obvious answer, of course, is a re-designed coupler box with a flat inside lower surface on which the coupler can ride, thus preventing the coupler head from dropping down below the level of the box....which is exactly what it does now. I understand the folks at Kadee are impossible to speak with and, apparently, are totally pleased with the design of their products, so a fix from them seems out of the question. The answer, therefore, must lie with another manufacturer willing to stand the costs to design and market a replacement.
Billybob