Gas Cooktop fitting fused

[Cody33432]

I have a used gas cooktop that I am trying to install. It was previously used without a regulator and the 1/2” fitting is stuck with the flare side out. I am pretty sure it’s fused together. Any advice?

Can I use this adapter to go from the stuck flare to the regulator?

LASCO 17-6789 1/2-Inch Female Flare by 1/2-Inch Male Pipe Thread Brass Adapter​

 

[Breplum]

Regulator typically goes right on the stub out of the cooktop.
The stub looks normal and there is never "fused" thread connections. With adequate leverage, threaded joints come apart.

 

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[Cody33432]

Thanks. I got it off. Took a little more force than I was expecting