K5400 margins increase when duplexing

[Jim212]

HP OJ Pro K5400dn  -  XP Pro SP3  -  No problem for several years, then this problem began about 4 months ago.

When printing duplex from any program, the top and bottom margins (portrait mode) increase exactly .75" when printing duplex, and the page contents and squashed as a result. That's a 1.5" total increase of the vertical margins. Really screws up the looks of the page.

When printing the same document single sided the margins are exactly what are called for in the program's page setup.

I have run experiments with several margin settings - the increase with duplex printing is always exactly .75" top and bottom.

I have many examples of documents printed duplex in the past which have the proper/expected margins. 

Any ideas on why this problem started and how to correct it??  Any help will be greatly appreciated!!   Thanks!

[ejf071189]

Just noticed I'm having this problem and found this post through google. I didn't realize the source of the problem was duplexing (it was even doing this when printing documents that were only 1 side of 1 page as long as the duplex option was set to "automatic") until I saw the OP's description, and have verified this on my own printer.