Chas, you and Karl really are the most generous and helpful people in the world! But no need to send the pliers as do have a pair I think will do the job.
Just to check one thing, do you mean I should bend the tensioner right back so that the spring is stretched. Also I've been working from undeneath the C5 rather than turning it on it's side or upside down. Is this the best way?
Sorry for so many q's this is the first real bit of maintenance I've done!
Dan