I gave up with the Koetsu, couldn't get it too work. Put the Benz back in and I'm now back to some nice vinyl.
Seems that toobluvr nailed it. I won't know for sure until the owner of the cartridge mounts it in his system and see if the problem is still there. I hope to find out from the owner how it performs in his rig.
Thanks for your help guys.
Rob S.