Ok, so it doesn't sound like a cross curve problem.
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?
I will show this thread to my tech guy here this weekend if he comes in and will fill you in on the cleaners we use ect.
Are you using Kodak ,Fuji, Agfa chemistrys?
Are you using automatic replenishing on the machine or manual?
Is there a long period of time between printing sessions?
Have you checked manually the tempeture of the developer and the bleach fix after the machine has been turned on.?
Immediate colour/density shifts leads me to think : voltage, dichroics, fogging problems.
Slow colour /density shifts lead me to think: contanimaton chemistry, improper mix, insufficient replenishment volumes, variation in chemical tempetures.
I do not think it is the paper as I think you mentioned that you have tried new paper . is that correct?
If you have thouroughly washed the racks , flushed the tanks and recirculation pumps and hoses as well changed the filters, I do not think it is your cleaning proceedures.
Honestly I think it is your dichroics / timer/ voltage/ or plain mechanical fluctuations of the enlarger.
Agfa chemistry, mixed carefully, and I've tried two batches of it.
Manual replenishing, but there's not been enough through it to exhaust the chemistry
There can be a few weeks between printing, but this did happen suddenly
Temps seem ok in the baths
Various new papers have been tried....
Its driving me round the bend! Hope it gets sorted soon, thanks for all the help, anyone else feel free to throw in some ideas......
Here is my last thoughts as now I am all out of ideas without seeing the prints.
take the neg out and determine a slight flash exposure with tone.
then expose 5-8 sheets one right after the other, do not touch anything but the expose button. process the prints.
if there is any variation it is the enlarger/timer configuration.
If you do not have a densitometer your eyes should be ok.
If there is no shift then :
try this again and adjust the dichroics. if you notice large shifts it would be the dichroics.
good luck and I hope to here how you solve this problem
Good idea, I'll try that!