Getting in a bit late, like a blister, after the work is done.
Here is how I fixed my mast base.
I needed additional height to get the rig tension right and discovered the wood under the base to be rotted.
Had not sagged, just rotted.
I think too much mast was cut when the step was installed on the deck thus the "long rig".
I drilled the holes shown and dug out the rotted wood and soaked the rest with resin thinned with lacquer thinner.
I packed the cavity with kitty hair bondo.
I backed the bolts out just as the bondo was firming up, applied a bit of oil and put them back in.
Note the shims I used to get the required height
Teddy
TJDSII6630