A6 4.2 V8 Crankcase vent valve buzzing noise.

[John Larson]

Sorry for the double post, the last one went without a message.  My 
bad!  OK, here's the issue.  I have a 4.2 V8 here in the shop with a 
buzzing noise (honking?) coming from the near new CC vent valve.  
Internet searches yield You Tube videos which perfectly portray the 
symptoms, but nothing in the way of diagnostics or repair information.  
I'd hate to throw another $132 valve at it if there is another possible 
cause.  Any tips, semi-informed WAGs, opinions, or pointers to a site 
where I might find help would sincerely be appreciated!

Thanks, John