This is what you use to seal the gudgeons, drain plug and pylons (or any other fitting for that matter):
To get the main traveller out of the track you'll need to drill out and repalce rivets, so unless it's broken, I'd leave it alone. Scrub the track really well with a brush and a grease removing detergent like Dawn. Flush really well with fresh water. That will clean out accumulated lubricant and gunk. Make sure to get in the groove on either side.
Once you have the track clean, give the track and traveller car a good shot of this:
I've never had to take the halyard sheave apart. If it's got sand/dirt in it, flush it really well with water and give it a shot of silicone spray or McLube.
Do a forum search for tramp tightening - there's a number of threads about it. Use the trick developed by Matt Miller - pre-bend the sidebars with the mainsheet. It works really well.