I have the same problem with my Envy 4500. Not only does a portion of the top not print but also several times througout a page. Just the top portion of the letters whether they are capital or lower case letters or numbers.
I couldn't get 80% but I shrunk it to 75% and still the same problem when printing direct from the internet. But if I capture the page with PSP 7 I can print the page w/o a problem but I cannot print an entire page only about 1/2 - 3/4.
This problem of not printing the tops of various headers of a page just started. I think it might be from the panasonic page itself.
I will see about printing out a couple pages on eithre my son or daughters' printer and see what it looks like.