Ok, so it doesn't sound like a cross curve problem.

Voltage?
Its going through a durst transformer and timer, that's all. No real fluctuation in exposures ever noticed though....

The dicroics do have a bit of play in them, but only at the extreme ends oif teh scale really.

Chemicals are new, and its been cleaned thoroghly.
I used a dot of washing up liquid, and rinsed it dozens of times after that.
Any recomendations for what to use when cleaning the machine?