Problems printing on HP 4015x printer using a2ps

I have recently replaced an HP laserjet6 with a 4015x, and files that
did print ok on the old printer now don't print properly on the 4015x.
But the files look ok when viewed using gv.

OS: HP-UX 11.11.
Package used: a2ps (either 4.13 or 4.14).

On replacing call to a2ps with call to enscript printing is ok. Is
there something in ps file that a2ps produces that is not absolutely
rock solid? I am asking all this because I think a2ps is more flexible
than enscript (variable font).

I can email the offending PS file separately if required.