I believe you say your scale reads to the nearest gram? So even if it's accurate it could still vary +/- half a gram. That might be a bit much? I was using my "roasting" scale (600 gm., reads to the nearest 0.1gm), again, assuming it's accurate. The other day I bought one of those pocket scales at Amazon (20 bucks); it looks kinda like a Star Trek communicator.
My coffee has improved since. EDIT: That scale is 50gm. capacity, and reads to .001gm.
I've had the same grinder as you do for years. Early on I quit trying to adjust dose by using the timer; I find single dosing much easier. I weigh the beans going in, and ideally it would be good to weigh the grinds coming out as well and adjust accordingly. I don't, but that's just because I'm pretty dialed in now.
That's a clumpy grinder; what distribution technique are you using? I used to do the WDT followed by a hard tamp. Here very recently I've been using a rank beginner's version of Stockfleth's move, followed by a light tamp--just enough to evenly press the top of the puck ~0.5 cm. below the rim of the basket. Coffee has improved on both of the machines I use, an electric vibe pump one and a lever machine. Drier spent pucks, and the bottomless PF no longer spits in my eye. Coffee's better too. My belief now is that clumps internal to the puck are not near as bad as a too-hard tamp wrt channeling, the hard puck building up overpressure and pretty much forcing the water to find some
path through that hard solid mass.
EDIT: I just now added WDT back into the equation by grinding into an espresso cup (has larger volume than my FB), doing the WDT, then inverting the whole thing into my filter basket and continuing as above w/ Stockfleth's. I'm having a nice cocoa bomb atm.
I dunno. I'm surely no expert; these are just ways I've seen improvement.
I use a dab of pure stevia extract to improve all but the worst sink shots.