Thanks so much everyone for your very generous replies, I truly appreciate it.
@Brett H, yeah I might even just take out the lower burr, not sure what/where the shaft part is exactly, but maybe I'll find something really obvious like a bird has flown and gotten stuck in there, or a giant red button saying 'Equalise Steps' haha..
@KK ah interesting about the threads, makes sense, they look pretty fine but not sure. And doesn't seem to be an external factor (well, not one that I can spot)..
@mycuppa, definitely am using well developed and rested beans (Honduras beans from a certain someone named Jeff...
Hmm I still have my Rocky grinder I could use side by side... but that's the thing, I really can't see it as being technique that's the issue (and I'd definitely be the first to admit and be honest if I'm struggling somewhere!), because I can get very consistent extractions on the same grind setting, yields/times are +/-1 or 2 grams. Just when I change setting it goes to extremes.
And may be a wobbly, but don't know how I can figure that out...
@K_Bean_Coffee, thanks heaps for the offer appreciate it mate. Like I posted earlier, I'm getting great consistency on the one setting, so that makes me think it's not a technique/workflow issue, I am a stickler for keeping things repeatable and to the 1/1000000th degree accurate haha... but I'm more than willing to honestly look at my technique again and treat it still as a possible factor. And there was the fellow from the other forum who did have issues with the steps, but yeah I've asked around and no one else seems to have issues.
Okay, current plan of action:
-take out bottom burr, clean out, see if any tree branches are stuck in there
-Keep all variables the same when pulling shots
Thanks guys, any more thoughts feel free!
Edit: or perhaps just more kgs of beans need to go through it to 'season' it?