This is a simple up-and-down hand control.
This is a paddle switch up and down with a straight 3 pin connector that usually connects in the pocket of your lift chair.
If you have recently been having to fiddle with the hand control to get the chair to move and now it will go up, but not down, or, down but not up, or, has finally completely quit working then you most likely have a bad hand control. Logically if the chair moves at all you know you have power from your power supply and your motor is able to move. Thus, your motor and power supply are most likely good. You can easily check your power supply with a volt meter. It should be putting out 25 to 33 Volts DC. (The hand controls are a bit difficult to test accurately. Often trying your bad one on another good working chair is the simplest way to test them)
About 85% of all lift chair electronic problems described above are simply solved by installing a new hand control. The hand control plugs in easily, just like plugging a keyboard into a computer.