Resistance when filling the tslim cartridge

I have had this happen 3 times. The first time, I started over with new cartridge, needle, and syringe. The other two times, I just changed the needle and it worked fine. I don’t worry about it any more and if it happens, I change the needle. Somehow I have extra syringes and needles related to when the cartridge tubing was changed 1-2 years ago and I kept the needles and syringes from the boxes of cartridges I had to discard.

Needle coring: wow, interesting thread, thank you!
New Tandem user here, have not yet received my welcome kit.
Is the gauge of the needle identified on the syringe, for the bigger ‘problem needles’?
Is there a way for the new user to tell (lot number, or documented gauge of needle on the packaging), that they are likely to have a needle coring challenge with their ‘the needle is too big’ syringes?

I had similar experience. In some cases, drawing up air into syringe (to inject to vial) indicated a problem, so switched immediately.