Samsung ML-3310ND horizontal lines

[REF4321]

I've just started to get evenly spaced horizontal lines, approx 75mm apart on my printed page. I've read it could be a problem with a faulty toner cartridge or fuser.

Is there anyway I can work out what the problem is other that buying a new toner cartridge and if that doesn't work then buying a fuser kit?

Any help appreciated

Regards

REF4321