I've owned the boat for 9 years, and it has never been done. Some people suggest that it should be an annual thing, but I think that for the length of our season, and the amount of boating I get in, that it can be stretched to 4 years. That means that I should have already done it twice.
It is not a complicated procedure. For Serenity's Barlow 15s, disassembly requires removing a single screw, and it all slides apart. There are no gears to be concerned about. The biggest worry is not losing the pawl springs.
A proper cleaning probably involves soaking the parts in a solvent, using a brush to get into all of the crevices, and giving everything a proper cleaning. I just used a paper towel to rub off what I could, and a flat head screwdriver to scrape off what was more resistant. At this point anything was an improvement, and I didn't have that much time to put into it before dark.
The winch was dirty. Much of the old grease was hard and useless. Only one pawl had much sign of life. The other two were very lethargic, and refused to snap promptly back out. This winch was not too many seasons away from failing to function at all.
After the cleaning, some light oil was applied to the pawls, while everything else was coated in a white PTEF lubricant. After being put back together, there was a noticeable improvement in the functionality of the winch.
The entire job took me about 90 minutes. If it was done more regularly, the cleaning would be done much faster. The next time I'd expect to spend less than an hour at it. That is, as long as I stick to the 4 year maximum cycle. Have you done yours lately?
Cleaned the starboard winch today, and it was actually worse than the port one. It might not have even lasted this season before giving problems. Something I forgot to mention, check the winch screws/bolts. All of mine were a little loose. That's the jib winches taken care of. The Harken B6A halyard winch is only a couple years old, but I might as well look at that one while I'm at it.