pile length issues causing lines

Kia ora everyone, I'm hoping someone could help to shed light on an issue I am having with my tufting gun.

I am getting lines in my rugs, and it seems be being caused by my gun cutting the yarn not in the centre of the loop (if that makes sense - I'm not sure how else to describe it). These short bits are very uniform and create short rows which are very obvious, no matter how much trimming I do. In some rows the short 'issue' pile is only 3mm long 😭

I've attached photos as best I can to show the issue.

This is happening on every row.

I researched it and came up with too much spacing causing lines, but I think my spacing is okay? I have attached a photo of my row spacing. I use two strands and also thick single strands. This issue happens with all the configurations I've tried, including wool and acrylic (expensive and cheaper yarn).

My yarn setup is loose and slack, and I have good 'drum' pressure on my cloth. I use good quality monks cloth from the tufting store.

This is a 2nd hand gun - I'm anxious to spend $350nzd on a new gun if the issue is a user-based one 🥲 (tufting supplies are spensy in Aotearoa).

Nga mihi 🙏