cartridge install issue

Hi all,
Quick question. Installed a new cart last night and although the sound is fine it is out of balance by about 2 feet. No amount of adjustment made any difference. When I put the old cartridge back on the sound was centered again.
my question is could it be the cartridge or probably installer error. Have set up many carts without a problem.
I did buy the cart used supposedly with low hour. I believe the seller. So its probably me.

your opinions will greatly appreciated

Matt