I do stop playing with him, and he always gets a good, firm no when he bites. He's sometimes pretty stubborn, tho, and he'll chase after me instead of whichever of his toys that I tried to redirect him to. Since this is a recent developement, I thought it might be due to his testicles having dropped and the accompanying surge of hormones. As it's not, I'll try to remain patient and persistant.
And he does have a mix of toys, some hard plastic with bells in, some plush ones with feathers on that he can sink his teeth into. Not to mention several wads of paper, since he seems to love paper most of all.
Thanks for the advice!