checking exposure with digicontrol strip

[EyeTech]

I've probably asked this before but can't trace the answer, so here goes.

We're running LAP-V plates thru' a Palladio 30. The digicontrol strip at the base of the plate is showing 1x1 circle clearly, 2x2 just discernable all others merged with background. 1 micron lines barely visible, 2 microns clear.

On occasions, particularly where pale tints are involved (say 4 to 5%) the tints break down and I have to drop the laser intensity. I'm sure we started off with an intensity of around 80 on installation (around 3 years ago) but gradually we've got down to 40 to maintain light tints.

Any input appreciated.