A quick search revealed that it is very common for the sealing strips to wear out, and replacement parts are readily available. The whole process of replacement should take about $15 and 15 minutes of your time.
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Step 1: Tools/Materials
-small long-nose pliers
-small needle-nose pliers
You will need to order a new heating element and some Teflon tape. I got mine from Elements and More for about $15 (and free shipping). Be sure to tell them to write "Do Not Bend" on the mailing envelope. You could probably use NiChrome wire or ribbon for a more DIY approach.