Poons does this type of lift have button modules that are specifically id'd for a certain level so you need to replace them with a specific part or are they universal going into a car module which is then decoded to tell what level has been pressed. The reason I ask this is if they are universal then swap the module with another level(not 7) and test it. If it works at another level, but with the module you just swapped it still doesn't then the car module is faulty. You can even do this if the are only programed for a certain level(fixed hexadecimal addressed button module wired in a serial data loop). Swap it out as I said and if it then does latch for the 7 button then the wiring to the car module either internal or external is faulty.