Are you looking for the element o-ring (attached below)? If not, I have attached the operator's manual. It lists all of the parts on page 6 with a diagram for visual reassurance.
Operator's Manual: http://www.etundra.com/ShowDocument...
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You can also find the manual under the "Learn More" tab above. I hope this helps! When you find the part you need, do not hesitate to call us to place the order at 1.888.388.6372.