I may be wrong but I seem to remember reading on here that there are 2 types of motors used with MX TV's which have a different number of pins on the lead which plugs into the TV.
If the plug is compatible with your LX then yes you can simply change the top plate. Unplug the TV from the mains before plugging the stand motor lead into your LX, then restore mains power or your TV won't recognise the motorised stand.
Chris.
The use of metaphors should be avoided like the plague. They're like a red rag to a bull to me.