I had a mast stuck for quite a few months - wouldn't budge (tried all the tricks). I finally got stuck into it with a rubber mallet and that did the trick. Separated no problem. 
It snapped rigging a couple of sails later. 
I've never had a mast that can't be separated from standing with feet shoulder length apart with hands at same distance, hold mast horizontal to ground at waist height and then shake vertically as hard as u can to cause bending or whiplash, watch the gap as u do it because after two or three good ones it can give u encouragement as u c the gap just increase. If this doesnt work then stand top end on the ground somewhere near your feet and point mast vertical and shake the bejesuz out of trying to get the same action as before, do this until your arms feel like jelly then get the guys to help twist, it has never failed 
I'm sorry to hear of your difficulty, Jerzy. It must be driving you crazy. Hopefully you have been successful ,but if not, before you try anything too radical I have sent this thread to a friend of mine who is an industrial engineer and pretty sure has worked with material like this... can you post exactly what it is made of? He may be able to assist...?? I hope so.
Duct tape is your friend.
Get a 2 buck roll at the Reject shop and tape 6 inches around your mast join every time you rig.
Your problem wont happen again[}:)]
Pity they dont make an overhanging rubber flap on the connector of the mast that that could help prevent this:( Flip it up when separated and down when connected.
If you cant get a mast apart using booms then you have rubbish booms. If you have no booms then you could just fabricate some oversized strap wrenches (would be best to have a few to spread the load)..
'Give me a lever long enough, a fulcrum strong enough and I'll move the world'..
Or just wobble it, as has already been mentioned....
If neither of these work then something is wrong, not the mast or separation technique.
And I don't see how taping the join stops sand, it gets in when people use the mast to dig holes in the dirt while rigging.. Or maybe up the extension when wallowing in the shore dump..
If there is sand getting in through the actual join then I'm a Monkeys Uncle.
i agree, not a chance sand gets in through the outside of the join. i do often get it in bottom rigging, rocks evrey now and then too
I think the sand gets in whilst rigging as the ferrule come apart a little a couple of times whilst sleeving, and sand from the luff tube gets in.
Many people report stuck masts on and off, then they tape the join and never have it happen again so there must be something to it?
Many people get their masts stuck in spots with sandy rigging areas.. Grassy rigging areas, hardly ever.. There must be something in that!..
I always take note when somebody gets a nice big scoop of earth up the mast while rigging, completely oblivious..
In other words..
Only noobs get stuck masts..
Have you tried separating the bottom from the top.
PS - If it's not apart by week ends I'm going to have to shoot myself.
My thoughts exactly Kato. I've never had a stuck mast at SP as I have always taped the join. The sand at SP is so fine it get's into everything too. Every year I've been there I have had to help pull someones stuck mast apart. Once you tell em about taping it doesn't happen again.
Someone here likes to think they know everything however [}:)]
Sorry to disappoint you guys but I have had masts stuck even when I taped them.
And I am really anal about keeping sand out of my masts!
It does help though. I think it stops water getting in. If there is a bit of sand in the top of the mast, all it takes is a small amount of water to wash that sand into the join. Then you are stuck!
If water can seep into the top of the mast from any source the damage is done!
Id go back to plan A. If it were my brand new mast and it got stuck the first time use that required a couple of people to get it apart. And now its frozen solid the second use i would be thinking its a problem with the mast not the way i used it. Take it back to the shop and ask for a replacement.
Is it possible for the mast conection to fit to neatly. Most of my masts have a little movement in them when you first start sliding them together and seem to get really snug in the last cm of the joint. My newest skinny mast however is a "perfect" fit and like a high maintenance super model this is causing me lots of problems. Mostly that I fell like a noob transporting my $599 mast on my ute with most of the mast waving around above the cab.
[insert gratuitous photo of skinny model]
I wouldnt mind betting even if you do get it apart no matter what you do to keep sand and water out it will get stuck again. You will end up hating the mast and possibly the brand forever everyone you meet you will tell them your story and warn them off buying that brand so not only will the manufacturer lose your business but probably others as well. I think its fair to give the manufacturer the opportunity to rectify the problem that way its win win you get a product your happy with and the manufacturer keeps your business and others as well.
Jez looks you forgot to try Adam. He has 100% success rate. Next time when you are at Bonno have chat with Adam.
I've had a couple of masts in the last decade that were super tight straight out of the bag.
Gave it a quick hit with some 1600 wet and dry.. Never had a problem with it sticking or jamming again.
Over time the do wear, but sometimes when they are brand spanking they are tighter than a fishes ar$e
Never had a jammed mast that couldn't be budged with the two boom method though
