Heater box.
 

Hello everyone, new member here. Great site you have here. Here's my question. I have just installed new heater boxes on my 1970 Beetle (which has a 1600cc engine). The spring that came with it is different from the original. The new one is straight in design, like a brake shoe spring. Where do you attach it so that the arm can spring back like the original. Thanks in advance. :)