Welcome to the SeeMeCNC Community

I have had a spool of ninja flex for a couple of years, unused. I'm certain I bought it from SeeMeCNC. Just ran a big part with it, that used most of the spool. It processed great, never a problem and part turned out beautiful. Wanted to build a duplicate so I went on the website to buy another spool, and I can't find it on SeeMeCNC. Ended up going to Ninja Tek? and buying a spool. It was expensive like $50+, and when it arrived I saw that it was way different from the first material. It is not smooth, more like serrated. And about 10 minutes into the build the nozzle jammed and it quit feeding. I just ordered some .5 nozzles, it was a .4 that plugged up. What happened to the "other" ninja flex?

You might want to give this a shot:
https://www.amazon.com/SAINSMART-Flexib ... 4-fkmrnull

g.

I also ordered a reel of NinjaFlex when I got my V3 kits.
The regular-flex was out of stock so I got 'semi-flex'? something like that nomenclature.
It's ancient, and apparently hydroscopic, so it shouldn't work at all,
but,
repeatedly produced/es outstanding prints, feeds well, no mods other than temp settings.
It is smooth and 'natural' colored.

I'm wondering if you happened to get the same stuff the first time... the softer version has all the issues you mentioned