Michael, thanks for the info. The manual has the 602 and 603 chain tensioner removal as the same document - so I am pretty sure they're exactly the same. So loks like it's regular socket.

Did you replace the chain tensioner seal? Do I need to?

Also, how long did the job take you? Taking off the camsproket, camshaft, etc. You see, I need to plan the after job beers to arrive naturally around sunset....

Cheers.