I've got a VonWeise on my Windgard and I wire brushed it and painted the outer tube with several coats of RustOlem paint using a 2 inch paint brush.
The inside of those screw housings don't have grease in'em, or at least the ones I've had apart didn't. The acme thread screw is cadmium plated steel and the nuts they use appear to be molded glass filled nylon. Over time that cadmium plating will still allow some rust to build up on the screw, which isn't good for that nylon nut!
The inner shaft seal out on the end is "suppose" to keep water and dirt out but they don't last forever especially if rust builds up on the inner tube. I have made new seals for the VonWeise with automotive radiator hose and SS hose clamps and only tighten the end that runs out on the inner shaft tight enough to make it seal. I suppose that those factory seals are still available from VonWeise though since they are still in business.
There is a thread here started by me that shows how I replaced the nylon nut with a brass one and I actually put a bunch of light grease inside that one to make sure that it had lube. It's been up and running now for over a year I think and it's doing fine. When I run it down to 139W it will pick up some of that lube, which collects at the bottom when the dish is up in the upper part of the arc. FYI, Here's a link to more info I posted on my racing site about nut replacement and some other stuff.
Motorsports Village • View topic - Von Weise Acme Nut Repair