Help with The Clockwork Labyrinth

The electric box needs a positive and a negative circuit with active transistors. The first task is to trace the correct circuits. There is only one positive circuit (red wires) that passes through both the Rectifiers (blue tops - left of centre) and the Resistors (red tops - right of centre). There is also only one negative circuit (black and blue wires) that passes twice through the Rectifiers. Once you have traced these two circuits, you need to remove and test each transtor on these cicuits in turn and return it if it is active (green light), or change it for another one if it is dead (red light).

is the closeup on the pipes puzzle doable or something else needs to be done first?

The steam pump is central to the maze and is not a puzzle you can do once and move on. The instructions on the back of the door tell you what is needed - its up to you to decide what you need to do and what is needed to complete the task. Sorry to be a bit vague but I don't want to give away too much!