Seriously, the timer thing is a game changer. I mean, it forces you to just get the messy first draft out, kinda like what @james_kim said. The real trick is accepting that first drafts are supposed to be bad.

Wondering if that weird ingredient might be the secret. My great aunt used to put a single clove in her brine and it made all the difference. Sometimes those old recipes have odd touches that actually work. I'd try it before writing it off.

Try adding a drop of pure pigment booster to your regular color mix, the kind meant for fashion shades. It doesn't change the base color much but packs way more stain. I keep a tube of red and a tube of blue for this exact reason... a little red-based booster on those stubborn front grays makes all the difference. You have to watch the timing though, or it can get too dark.