Bottom end rattle

[luke906_uk]

When at low rpm sub 1200, there is a noticeable rattle coming from I believe the crankshaft. I've investigated for worn end bearings(shells) by removing the crank end cover and holding a 14mm spanner on the nut that fixes the timing plate and tried to move the shaft up/down, side to side to check for play. There is no play however, there is rotational play (a degree or so each way). Is this normal? Or is this a sign of worn primary chain/sprocket? I've ruled out the clutch as I've done the mod on the oil pump drive to take out the play. If however the idle is higher around 1400-1500 or the throttle is blipped, the rattle disappears. Any suggestions or other probable causes? Cheers