inspected timing, timing chain and tensioner

[TUBBY-DEUCE]

first of all i checked the tensioner, all seemed well. i took the cam cover off to inspect the timing chain and the chain was slack over the cam sprockets, i turned the crank clockwise without the tensioner in and check timing, the timing was ok and the chain is nice and tought now, im goin to get a new o-ring for tensioner and reassemble.

does anyone have any ideas why the chain would have been slack until i turned crank?