I think this may help with your problem.
Download this manual and refer to page 14:
http://www.pickyourown.org/canning_e...structions.pdf
Refer to this page for additional sealing ring info:
http://www.pressurecooker-outlet.com/7.htm
Be sure to read questions and reviews by purchasers(feedback). There is info on seal install:
http://www.amazon.com/Presto-Pressur.../dp/B000LL9NY2