sorry to take so long to answer your post.
Barient went out of business in the mid 1990s but an Australian company bought out their tooling and is still making most parts. You can go to their web site at http://www.arco-winches.com/products/spares and order parts bearing in mind that you will have to pay exorbitant shipping costs from Australia. If it is just pawls, springs and common bearing races, you need you can order them through West Marine or APS. In regards to performance, both brands will do the tasks at hand. New Harkens definitely look sexier and the support is outstanding, plus newer winches will have better grip on your lines.
Performance wise the biggest difference is how worn the grip surface of the winch is and how well it is kept up - cleaned and lubed. The Barients can be knurled at a machine shop on a lathe to restore the surface grip. Not sure parts are still available for the Barients.
The newer 35 power Harkens 35.2s are slower but more powerful than the 24 power Barient 19s. The Harkens are much easier for less powerful crews but if you are strong enough the extra power is unnecessary. I used 10" handles with my Barients but the last lost handle was replaced with an 8" for my Harkens
The old Barents have two problems - both fixable.
1) The pawls tend to fall out of worn drum sockets. You may be able to fix the socket with JB Weld or if not then epoxy suitably shaped 1/16" thick pieces of aluminum at the sockets edges to keep the pawls in. The pieces start out about 3/4" x 3/8" x 1/8" then are filed and fitted until you can see they will hold the pawls in and will allow the range of motion needed. Then epoxy.
2) The drums tend to wear smooth. You can have them knurled but if you are cheap, you can etch the surfaces with sodium hydroxide (available on line but read and heed all the warnings). Be sure to mask off the areas you don't want to etch.