C220 Prints on side 1 never line up with side 2

[Guest]

We have recently purchased a used Konica Minolta C220 to produce low volumes of flyers, but if printing duplex (whether it be manual or automatic), the print on side 1 is never in line with the print on side 2 (about 5mm out).

I would really appreciate it if someone could advise me on the best way to resolve this.

Thanks