Yes I did refer to that guide during the work Martyn. Can chain tensioner appears to work fine, does pick out etc. but it's impossible to know whether the 'force' exerted is to specifications of not.
I really need someone who's seen a 'good one' to tell me whether this is in spec or not. Someone must know if it's too much ?
My rule of thumb is to look at how the timing lines on the camshaft sprockets align with the head. They should look like this i.e. parallel to the head casting:
If the chain is worn then the lines are over at an angle as shown in the photo below:
There is a guide to replacing the timing chain here.