Unicode Corruption and upgrading to 8.0.4. to 8.1

[Howard Cole <howardnews@xxxxxxxxxxxxx>]

Hi everyone, I have a problem with corrupt UTF-8 sequences in my 8.0.4 
dump which is preventing me from upgrading to 8.1 - which spots the 
errors and refuses to import the data. Is there some SQL command that I 
can use to fix or cauterise the sequences in the 8.0.4 database before 
dumping to 8.1?

I think the problem arose using invalid client encodings - which were 
not rejected prior to 8.1.

Regards,

Howard Cole
www.selestial.com