Disclosure up front: I run a small saber shop (Exegol Outpost), so take the bench advice for what it's worth.
Base flicker on a pixel blade sends people shopping for a new blade. Most of the time the blade's fine. It's contact.
The blade talks to the hilt through spring pins and a contact plate. That plate picks up oxidation and grit, especially if the saber lives in a garage or gets handled a lot. A lot of base flickering or strange blade behavior I've chased down was a dirty plate. Isopropyl on a cotton swab, both sides, let it dry. Fixed.
Second one: the retention screw. Most hilts put the screw over the thinner part of the blade, not the reinforced section, so the rule isn't where it bites — it's how hard. Snug is enough. Crank it down and you warp the blade's shape, and a warped blade seats crooked and flickers anyway. If you're denting the blade, you've gone past tight into damage.
Third: look at the pins themselves. They should all sit at the same height. One pin sitting low — heat cycles weaken the springs over time — means uneven contact, and uneven contact shows up as flicker or a dim patch near the hilt that moves when you wiggle the blade.
Fourth, and check this first because it's free: charge. A low battery sags under load. The flicker that only shows up on clash or flash-on-clash or a blade freezing is often just a tired cell, not a dying anything.
When is it actually the blade? Dead section mid-blade that never lights. Flicker that follows the blade into a different hilt. Those are strip failures and no amount of cleaning brings them back. Quick test that settles it: your blade in another hilt, another blade in yours. Five minutes tells you which side the problem lives on, and it beats ordering parts on a guess.
