I know there's heaps of threads about stuck booms but thought I'd jump on the end of this one.
I bought a second-hand ally boom from a shop and had it shipped to me. They did mention at the last minute that it was stuck but I figured I'd get it loosened.
Well so far I've given it the couple of days soaking in the pool, the vinegar treatment to the point if I ever sail with it I'll be wondering who nearby has some chips

and then moved onto WD40 multiple spays.
One side has released but the other side is holding tight. Frustrating as the boom now flexes as I'm trying to release the stuck side.
I've hooked it over the tow bar of my car and belted a 1 foot piece of dowel placed at the end of the boom during multiple sessions. I now have a piece of dowel that is about 10 inches long (and a sore hand ... I miss from time-to-time). It ain't budging.
Where to next?
Do I repeat the previous steps?
Or perhaps tie the end of the boom to a tree and go gently on the accelerator with the boom around the tow bar?
I can't comprehend how it could be THAT jammed up???
Any suggestions appreciated