Please don't fall into the logic trap of measuring one heater terminal to ground or neutral. It doesn't work that way. To meausre heater voltage (aka the complete circuit being made) you MUST measure between the two heater terminals.

Here's a diagram for you intense folks...
http://spapartsnet.com/voltheater.gif

Please follow it. If you don't understand how to make these measurements after looking at this, then please call us.