I'd definitely say a vet visit is in order. I hope it is a parasite or skin disorder, because my first thought was self-mutilation. Once those sorts of habits become ingrained, they're really, really hard to sort out!
If the feet feel dry, you could dab on a bit of cooking oil and smear it over Echo's feet to see if that improves things. I don't think a tiny smear of oil will hurt him and it might give him some relief. DO NOT use human medicines or ointments on him, as you don't know what effect seemingly harmless things like lanolin could do to a birdie.
If you think it's more a behavioural thing, you could test Echo by swapping his toys out and replacing them with a few new and interesting chew toys (eg. bits of wood, cardboard packaging, plastic bottletops - anything that's new or different to him so he'll be engaged with it for a while). If the biting improves, that would imply he's bored.
I'd still visit the vet, though, because if the feet have been bleeding you'll want them checked for infection. Please do let us know how you get on! We can't be having a noble Alexandrine in trouble, now can we? Barney and Madge send soothing cheeps to Echo and hope he feels better soon!
