Today I checked the base level noise and got 4uV. This did not improve after an hour of a warm up.
I used a copper strand with Q-tip to short the inputs. This seems too high.
not sure as to whether you are talking about "noise" or "offset" here, so i assume that you mean "offset"
after cold start, (instrument was off for 24 hrs) my specimen needs about 2.5 hrs to fully settle from approx. 6µV to some constant offset value (set to DC, 200mV, 10NPLCs, no FILT, input shorted).
i'm not concerned about the constant offset, as that will be fixed, once the instrumet has got a calibrate/adjust run in a cal lab. also, that constant offset value is "rock stable", i.e., even after a continuous run for a month, that offset didn't change at all (well, it did change with ambient temperature, but always came back to same value for same temperature).
but i am wondering whether the amount of initial drift of several µV has to be considered too high, and might point to some hidden fault. otoh, the instrument passes all self tests.
so, would be great if you could post some of your offset values wrt time here
as for "noise", have look here, where i posted some values that may be helpful for further performance verification of your 2002. note that i've used quite a small sample window of just 50 samples, so take them with a grain of salt. should be fine for a q&d performance check, though.
https://www.eevblog.com/forum/repair/keithley-2002-repair/msg1188312/#msg1188312