My wife's '93 240 has an OEM power antenna on the rear fender. Lately the middle section of the three-section mast is jammed: the outermost section rises, followed by the innermost; but the middle one seems solidly jammed!

I even tried, as it rises, grasping it with pliers (not enough to crush it, though), and it won't budge. Very, very stuck.
I've also tried various lubricants (WD40, silicone spray, etc.) -- and have always gave it good care in the past (wiping the mast periodically with silicone spray to ensure that it moves easily), so I don't know why it should have jammed. Anyway....

... trying to avoid having to buy a new one ($$$, ouch!), has anyone ever had any luck dismantling it? I've taken lots of things apart (and put them back together properly, the most important step :-), but...
has anyone been able to repair a problem of this sort? I figure that I might have to replace the mast -- are replacement masts available?

Any advice is appreciated.
Thanks, all.