Hi Mike,
We had our Seal 22 Elsa (122) for 16 years.
In my experience the maintenance has mainly revolved around the raising and lowering mechanism which can be accessed from inside the boat with the table top removed and the keel pinned in the up position (see Seal 22 Hand book for details), which only required an annual inspection and re greasing.
It would be advisable to inspect/ replace the keel lifting strops.
I inspected the keel annually when the boat was in the hoist before going back in the water, the only maintenance on the keel was an annual antifoul.
One year the keel was striped and re-coated, to do this the boat was left on a trestles cradle with the keel down.
Regards
Denis
P27 Selina 158