Inconsistent E steps tuning results

[gwes]

Hey Team Teaching Tech.

Not totally clear if it's ok asking for help with a specific issue here or not, if not please accept my apologies and close the issue.

However if it is....

I acquired an Ender 3 v2 from a friend but have been having inconsistent results. Decided to go through the TT calibration steps to try and dial it in and work out where the issue is.

I am having some inconsistencies when trying to setup my E steps. Printer was set to something like 103 (I forget now) and left about 17mm of filament, the site said to try 101, which I did and it gave me 30mm remaining, suggestion was 111. I ran the G1 again and that gave... 30mm left... WTF...

So, I think my issue is probably that the stepper is slipping or that something is restricting the flow of filament. The print results are I think consistent with that as the L1 test squares print patchy, like there is just the right amount of squish / filament in places but then voids in other areas. If I heat the hot end and push filament through it does seem to come out ok but obviously that's not particularly scientific. I did change the brass knurled wheel thingy that's attached to the stepper as the previous one looked warn but that does not seem to have resolved the issue.

I guess my question (thanks for reading so far!) is; How best to go about diagnosing this problem. I assume I set E steps back to 100, take some bits off, re-run the test, take more bits off, etc, etc until I get some consistent readings?