Trouble with refillable injection pens?

Really would avoid reusing cartridges whenever possible.

Ended up doing it once when my restock got delayed in transit, and by round two the plunger had already started catching. It warped, jammed on one side, and then the plastic ratchet mechanism on the pen itself started bending...

Noticed it wouldn't budge, so I dialed up a few extra units and tried again, still nothing, dialed more, still stuck, then suddenly it released all at once and I'd accidentally given myself about one and a half times my intended dose.

Zero out of ten. Wouldn't recommend that route to anyone.

Same problem shows up reusing needles too. My theory is certain peptides clog the needle tip if left sitting for a week or so.

Whatever I inject daily doesn't usually run into this, except for the copper peptide, which I also take daily and it still occasionally refuses to flow. (Again, not actually recommending reused needles, but desperate situations call for desperate workarounds, you know how it goes.)

That looks like the older pen style. Looks like four doses used already. There's still one more left in there. Draw it out next week using a syringe with an insulin needle already attached.

That's assuming your pens match the UK version.
The newer style has an extra bit of black plastic tacked onto the plunger. That added length is how they get away with putting less liquid in each unit.

Damn, sounds like you've done all you can. Have you tried moving the stuck cartridge into a manual pen? Others have reported this, then moved to a manual pen and still fought it, and all anyone could come up with was bad glass or a crooked plunger. Did all the cartridges come from one maker? Budget manufacturers sometimes skip lubricant.

Same feeling here. I thought my pen was broken and held only 3 doses, but after the 4th yesterday there was a little liquid left. I bought mine mid April though, and I thought they hadnt rolled them out yet.

I'd say cheap cartridges have doubtful sterility, endotoxin and manufacturing residue issues. Factory rejects keep reaching us, with out-of-spec genuinely vials, stoppers and seals, which give unreliable dosing and wear pens out early. One of my pens jammed hard around a month ago. My mom, 85, told me her pen was giving her trouble, and I'd considered it indestructible. When I tried injecting her it locked up completely. Luckily I had a spare cartridge on hand that fixed it. Racing to the bottom on price is a loser's game.