I've given this tip before:-  Use a small soldering iron.  Poke the
end into the tracker bar nipple with the remnant of rubber tubing still
on it and wait 10 seconds.  Move the soldering iron to the next nipple
whilst you slip the now-loosened rubber stump off the first nipple with
a pair of tweezers.

The whole process of 88 nipples takes only minutes and the tracker bar
acts as a huge heat sink, so there is no possibility of de-soldering
the nipple.

Regards
Nigel Perry