I was fishing the other day with a very old Wiggle Wart and I noticed that the action went dead. I cranked it up next to the boat and gave it some slack and sure enough it sank. Easy enough to fix.
You need to put that bait in the freezer for about 24 hours, then you will need a CLEAR drinking glass.
Fill the glass with water that is pretty hot, not boiling.
Submerge the bait in the glass and wait a few seconds until the air inside of it expands and forces bubbles through the hole where it is leaking. It is usually on a seam or around a hook hanger. If you don't see it the first time put it back in the freezer and try again.
The repair is pretty simple. First you will need to drill two holes in the belly of the bait. About 1/16 or 1/8 diameter is good.
Shake the bait and water will come out, you can blow into one hole and force it out the other.
Leave it dry for a day and then mix some five minute epoxy glue and seal both holes. You are good to go.
I have never had one leak after I repaired it and it is just very easy to do.
Maybe someone else knows another method, if so I would like to hear about it.