DB9 Top Gear Track
AO Silver Member
Join Date: Jan 2007
Location: United Kingdom
County: East Sussex
'reset' is the wrong word, it needs to be rotated against the very heavy spring.
You'll need an open-ended spanner on the nut in the centre of the tensioner (the bit that spins), on the other end of the spanner hook a long ring spanner forming a sort of dog-leg lever, then pushing the bottom of the ring spanner right/up has the effect of rotating the tensioner anti-clockwise, it requires a fair bit of effort to move.
Hard to describe really, and you'd think doing this would undo the nut but you're applying pressure in a way that moves the tensioner rather than undoing the nut.
Hope this makes sense, I've re-read the above and it sounds ridiculous - but that's how you do it.
All the best