You could also try drilling the hole out, slotting a bolt and washer through it and bedding it down in epoxy or silicone mastic and running a washer and nut onto it from the outside.
The compression on the two washers seals everything tighter than a mormon's arsehole.
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Overhead, the Albatross hangs motionless upon the air,
And deep beneath the rolling waves,
In labyrinths of Coral Caves,
The Echo of a distant time
Comes willowing across the sand;
And everthing is Green and Submarine
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