When printing envelopes with a LaserJet Pro M401dn, the return address is not properly fused, and there seem to be some random blotches printed in the stamp area; the main address is properly printed and properly fused. I noticed the problem with greeting card envelopes, which I’ve never had trouble with before on three previous LaserJet printers (LaserJet II, LaserJet 5p, and LaserJet 2100). With some #10 envelopes, the return address is properly fused but I still get the blotches in the stamp area.
I get the same problem if I fold a sheet of regular paper in half and pass it through the envelope feeder. If the envelope feeder is empty and the paper feeds from the main tray, the return address is properly fused but I still get the blotches in the stamp area.
There are no problems when simply printing documents.
I seem to get the same results using either the PCL 6 driver or the PCL 6 UPD.
Any ideas?