guinea pig bites

Question
I have kept guinea pigs for 20 years and am very familiar with nibbles and accidental bites.  I now have a 7 week old Abysinnian male who seems very friendly and is very vocal - he's very happy to be picked up, fed treats and held.  He does not appear to be afraid in any way.  But every time I bring him back to his cage he bites hard - drawing blood every time.  It appears to be intentional and not playful.  My hands and wrists are covered with bites.  He does not bite while in his cage and being petted.  He doesn't usually bite while sitting in a lap - just while being carried back.  I know the proper way for carrying guinea pigs and do not think anything I am doing is frightening him.  Do you have any suggestions for breaking this behavior of biting?

Answer
Well at first I would have said that it sounds like he doesnt like his cage but then if he doesnt bite when he is in then it is a little more confusing. I doubt it is fear either, when afraid guinea pigs very rarely bite, and if he is happy to be petted then I doub he would really be afraid of you.

the simplest thing to do would be to have a hidey house that you can put him in and pop back in his cage, I myself use a hedghog house to move three guinea pigs that live together at once.
this would stop him form being able to bite you but might not break his habit. for nips and biting what is usually recommended is to pinch at there fur with tweezers to mimic a bite from another guinea pig. this might seem a little druel but it is there way of letting the other guinea pig know that this is not acceptable. I have never really had to do this, a tap on the head with my finger is normally enough to stop a nip. Another tip which I have at times found useful is a water spray, when they bite they get sprayed, it works on cats, dogs and I'm happy to say on guinea pigs too, of course it would be hard to do while carrying him.