I take the bottom of the coil and sand it real good with some 120 grit sand paper, and it has to be silicon free if you use that before. Make sure no dampness is in the joints that are cracked.
Then I take some 60 grit and scratch the inside of the coil cover..where all the sand collects.
Next I take and mix some epoxy, slow dry....24 hour stuff. And in a spot where you don't mind a big mess.
I pour the epoxy into the coil cover, with plenty to spare. Making sure the coils is totally clean I set the coil into the epoxy filled coil cover.
A Big mess but it works perfect. Sealed for life..
Important, make sure you mix the epoxy as recommended so it will dry correct.
Give it a few days and go for the treasure!