Help with artifacts on burn

Hi. I’m trying to figure out why I’m getting a little line artifact after laser moves (bottom left hand corner of square). It’s almost like a ‘bounce’ is happening. I’ve replaced belts, tightened and loosened eccentric nuts, disassembled and reassembled, and sunk 2-3 hours per day over last 2-3 weeks (probably 6 hours today on this alone). It used to be fine, but it started happened after I tightened a belt and I’ve never been able to get rid of it (except when I really tighten up the eccentric nuts, then the squares end up all squashed! ).
Seems to be worse when I print towards the right hand side bed of the laser, but on the left side of th ebed its not showing as bad, but I do see a darker corner on each square.

I’ve got a OLM2 LU1-3. Given the amount of time sunk into trying to fix it, I’m wondering if I should just replace the whole lot (I’m in despair over it :cry: )?

Can you upload the .lbrn file that created the sample? Would like to review the laser path.