When I removed the lead tubing from my Ampico tracker bar, I was
told to take a box cutter knife and slit the side of the lead tubing
and then give a twist to the tubing and it should usually come off.
You may have to put a screwdriver in the slit to open it a bit more.

The old lead tubing came off my tracker bar pretty well.  Naturally
you don't want to cut through the lead tubing, too much, or else the
knife scratches the brass tubing on the tracker bar.

Well, that is my 2 cents worth.  Best wishes and have fun!

Musically,
Larry Norman - from the Blue Ridge area where it is warming up in 60s
with some rain.