Chris, the silver panel is hiding a heavy weight. If it's on a funny angle, it might just be dislodged in transit. Hold the tone arm firmly and you should be able to lift the silver panel and weight out. Might be an idea to take of the cartridge first to avoid Mobing it. You should then be able to slide it back into place correctly.
With the weight on and the cartridge on, if you slide the weight selector (next to the silver panel) to 'zero', the arm should be perfectly balanced. You cant play a record like this though, so slide it back to 1.5 grammes.
You say you haven't even seen one of these before, whereas most of us were weened on these. It won't move across without a record on the platter. The grooves on the record effectively pull the arm across.
If it doesn't lower at the start of play, and it doesn't raise at the end, then inside, a little brass pin has got stuck in a brass sleeve with lubricant which has aged and solidified. If this turns out to be the case, then we will talk you through how to fix it easily.
Keep us informed, eh.
Andy T.