I've had 2 Comet base loaded 2 meter mobile antennas degrade after a
year or so apparently due to condensation inside the so called sealed
base coil. I've now drilled a small weep hole near the bottom in the
second one and it seems to be drying out and working again.

There is no such thing as a sealed container outside. You need a
small hole to let the water out. Water will always get in by
condensation.

Mark