I almost always replace the lead tubing on Standards.  I learned long ago
patching is not worth the effort.  I cut off the tubing near the tracker
bar nipples and let it soak in denatured alcohol over night. The shellac
softens enough to allow you to pull off the lead tubing. It may take a
couple of soakings, but you can work on something else-those dry
pneumatics maybe.

I use a number 8 round head screw turned into the lead on the board end.
Then I use a small pry or hammer to pull them out. I enlarge the holes to
7/32 and use left over hammer shanks (from new hammer jobs) to plug the
holes These are about 1/2 to 3/4 inches long-just right. I drill these
out to 5/32 and glue in new nipples. Re-tube just like any other player.
A little lubricant on the tracker bar nipples helps the tubing go on
easier.

Jeff Davis, Seattle