3000 user here
2000 was the one with the potentiometer bank along the side, that you set more otr less once, no?
In mine you fiddle the color balance inside the unit by changing memeory registers.
They do work on the same principal.
In mine the 'slope' control is used to adjust for paper exposure reciprocity failure. I have never user anything other than 0 - the equivalent of linear.
I aim most of my exposures between about 4 and 10 seconds, so reciprocity is not a big deal.
I am pretty sure the way that you calibrate it is to print a test patch (grey will do fine), at say 5 seconds. Then stop down 2 stops on the lens and print for 20 seconds. If the patch comes out lighter, then you are experinecing reciprocity failure, and you will need to bump up the slope a bit to get the same grey tone on the 20 second patch relative to the 5 second patch. Even at 20 seconds usually is not a big deal. I think that the thing was really meant for those who go from a 8x10 proof, and then want to tilt the enlarger head and print a mural.
Slopes higher than zero makes, for example, a time of 20 seconds on the display turn the light on for longer than 20 seconds in reality, despite what the display time says.
Beware dry down; evaluate both patches either wet or dry but not one one way and the other different.
I have a Lici unit; some are badged as Jobo; who imported them, and relabelled. The 'downfall' of the lici approach championed by Jobo when they brought out their own colorline analysers is that they had different slope setting ability for each color, which the lici doesn't.
Nick Zentena used to have a 3000 colorstar manual pdf on his web site; I 'm not sure if the site is up since he moved to Italy. I bought mine off the bay from Portugal, and changed the plug and voltage setting, but the OEM manual is of no value to me- none of its langauges are ones I read.
Anyone know where I can get a copy?
