Further to this re-set problem I posted. I've found that clicking on the SSC icon on my desktop opens the window showing ink levels, configuration tab shows my printer model, but the reset tab shows 'unsupported chip'.
HOWEVER - there is another SSC icon in the bottom task bar - when I right click this, all the options are displayed in a small menu window.
I chose 'Protection Counter' clicked 'Reset counter' in the sub menu. Then I clicked 'Show current value'. It showed zero.
Sent a page to the printer. The error message on my computer had disappeared and the W-01 message did not appear in the printer's window. Don't know how it worked, but it seems to be solved.
My oldish PC is operating on Windows XP.