I bought a new DeGraaf double axle last year and when I went to collect it, the owner fired a lot of very useful tips my way. Needless to say I couldn't remember half of them when I got home, but I will get in touch with him and see if I can persuade him to add a servicing page to their web site.
2 things I can recall which are extra to the other tips you've heard on this thread....
1. Pre and post season, remove the cables, suspend vertically, make a plasticine cup at the top, around each cable. Pour in some diesel and allow it to soak down through the cable. This protects the cable and does not trap dirt and water like grease does. [His advice, not mine, so I can't vouch for it].
2. On each wheel and drum assembly, idenitfy a suitable spot and drill through the wheel and drum (without damaging the brake assemblies
), fit a male Hozelock fitting to the hole in some ingenious way, and voila, you have a ready made system for flushing your drums with copious amounts of fresh water at the slipway, when you pull her out, before setting off home. You just need to carry a female Hozelock fitting with you to attach to the slipway hose.
All the brake system components should be suitably greased anyway (apart from the brake surfaces of course, thought I'd mention that before some other wag does
), so all you're doing is getting rid of the salt from any exposed surfaces.
The water will naturally drain through the gaps but with enough water pressure you ought to be able to get plenty of water into the drums. If you can't, nothing stopping you rolling forward or back a few feet to circulate it.
I've bought the bits for this job and should have it completed in a couple of weeks, so I'll let you know how it goes.