After 22 years I expect the stern gland probably needs re-packing. I think that would be a fairly straightforward process, though much easier done when ashore. If nothing is significantly damaged, it should give another 20 years service using the occasional squirt of grease.
As the owner of a Falcon (aft cockpit version of the Seahawk) of a similar age for 4 years, I would recommend changing to the Volvo shaft seal. This is a single rubber moulding that has a manufacturer's quoted service life of 7 years I think but anecdotes tell that it can continue for much longer. i suppose your sailing environment may affect that - muddy, silty water may wear it out quicker, as I guess will drying out onto mud.
To fit it, you need to disconnect the prop shaft from the back of the engine, remove the old stern gland, check that the shaft is undamaged at the seal area, fit the new seal (2 Jubilee clips secure it) taking care to protect its lips with the supplied tool, give it a wee squirt of the special grease, reconnect the prop shaft and continue.
It's more than a 5 minute job but not a terrific amount of work, and well worth it for drip free sailing, I think.
You need to get a seal of the correct size, involving measuring both the shaft diameter and the stern tube diameter. Volvo places can supply them, such as http://www.volspec.co.uk/
Hope that helps.