Yeah I mean I see what you’re saying. Just pulled it like a puller would. Overtorque it til it pulls out.

Since you already have a replacement insert, measures its length...

They appear to have threads down their whole length. If there are 20mm of spacers above the stem, that means that there should be decent insert length left if you just cut the steerer with the insert in place. You may need an M6 tap to clean up the first thread after you cut the steerer/insert.

Easy peasy, not sure what the fuss is about.

Cervelo's been doing the glue-in insert for ages. Back in the round steerer days, it was just an aluminum sleeve with a 1" starnut inside - depending on how much length needed to come off, we would cut the steerer/insert and then tap the starnut down, or install a new one.

I always recommend cutting flush with the top of the stem and running a small spacer on top, for full clamp contact.

Spoker beat me to it ,don’t aim heatgun at fork directly ever ! the bolt needs to get hot enough to warm up insert and in turn soften the epoxy ,when heated nearly all epoxies ‘soften’ ,they can never return to their liquid state prior to curing but will soften ,the bolt needs to be too hot to even think about touching with bare hands,if outside of steerer is getting warm you are there or need to back off ,a very long bolt will [A] give you very good leverage to wiggle plug free [B]make you keep heatgun from being anywhere near being aimed directly at the composite ,I’ve used this technique to free bottom bracket sleeves and almost anything alloy bonded in composite frames and to remove fin slots in rowing shells and steel[rare] or alloy inserts in carbon riggers for same

After further investigation, the insert was the expanding D-shaped plug the whole time! Doh!! I didn’t even notice it before, the top looked pretty seamless and the bolt head was down far enough I couldn’t see the hex opening above the threads.

Now I just have to decide how much of the steerer I’m willing to cut off.