We had a retriever before who mouthed a lot, but we got through that and she learnt bite inhibition well.
We're using the same techniques now with our cocker pup but he just gets excited and does not stop.
When our retriever was mouthing we did a high yip sound and she would stop. We then redirected onto dog chew toys. This does not work with cocker pup, so we say a firm "no biting", put him in "time out" in his pen whilst ignoring him for a few mins, then let him back out. Rinse and repeat!
Is this normal for cockers? What worked for your pup?
[We are doing the socialisation, different noises etc and some basic training commands during the crucial window so he's getting a lot of other input.]