H-Block cleaning?

[YNOTBOB2007]

I'm in the middle of replacing all my soft lines with new ones and am wondering the classic "while I'm at it" dilemma. All manual drum brakes....69. Is there a way to clean the H block while the hard lines are removed? Unscrew that end screw? I just want to be sure I'm getting full braking and nothing clogged or dirty in there. I lost the rear brakes with a broken line years ago and never reset the warning light, so I'm sure the plunger (or whatever its called) inside is not centered. Does that matter? But I'm also afraid of messing with it if it doesn't need to be...law of Murphy. Thanks!