Having been the owner of both a V600 and a V700 windlass, I have a few comments on the design. First, the seal at the top of the shaft, where the capstan fits on has to keep out sand, mud, water, you name it. By the way, this is true for any vertical windlass. Second, Lewmar claims that the new V700 seal solves that problem though it's too late for a V600.
It turns out that that seal on the V600 was bad and let everything in. So Lewmar did 2 things. They started manufacturing their windlasses in Thailand and (somewhat) redesigned the windlass. They claim that the new seal is better. I do point out that the capstans are interchangeable, so I'm not sure what the redesign is. However the V700 has worked, though only for a year or so.
I'd appreciate if anyone else who has a V700 would comment on their experience, good bad or indifferent. I also added a washdown pump to try and reduce the crud on the line going through the winch. Also, I notice that Defender is selling motor and gear assemblies for the V700, so you can rebuild it, if you want
Here's the sand I pulled out of the V600 when I took it apart. Unfortunately, by then I'd replaced it with the V700. Live and learn. Notice the crud came down through the gearbox into the motor; got everything on the way down.
Boris