HP printer Model : V 40 , about 5 years old

Question

I am facing a serious difficulty : -
The print outs that come out have a problem -
every alternate line is only top half printed ?
Making the print out extremely difficult to read .
Please help .
Kashyap Patel .
Das & Company ,
Das Chambers ,
25 Dalal Street , Fort ,
Bombay 400 001 .
Phones - 022 - 2267 3661 , Fax [phone] .