Fuzzy sound errors are a clear indication of Paula problems. Replacement is not trivial and Amigakit don't do it.
Send the board to Antony Hoffman (
Castellen in this very forum) in New Zealand. Top service, cheaper than Amiga Repair Centre (in France: again a top of the shelf service, but expensive).
Since you didn't provide your location in your profile is hard to tell which service is nearer to you.
