Thanks to Tim Messenger for his clear instructions on removing the top plate: http://www.rangefinderforum.com/foru...ad.php?t=31755
The only things I'd add are: (a) make sure you have decent jeweller's screwdrivers (some of those screws are tight!) and (b) when removing the rubber grip, the double-sided tape was damaged in places, so have some strong double-sided tape to hand in case you need to replace areas of the original. As Tim says, it's easy to remove the top plate, but do take notes/sketches/photos of the shutter-speed dial and cocking-lever assemblies.
I'm attaching a PDF showing an exploded view of the camera, which should help - this is available on the Internet, but it can't harm to lodge it in this post as an attachment.
My shutter-speed-dial lock button has been intermittently jamming, and on removing the top plate I found the cause: a thin sliver of something (wood?) had worked its way down the button shaft!
With the top plate off, I took the opportunity to disable the shutter-speed-dial lock button entirely, as I've always loathed it: the lock button is one of the camera's few poor ergonomic points, IMO - it's unecessary, and, if the exposures's off by much because the dial's not set to AE, the shutter speed blinks in the viewfinder to alert you anyway.
So, I jammed the mechanism to permanently depress it, using a piece of rubber - ensuring it was securely placed and couldn't work loose. (The mechanism's spring is now permanently tensioned - not ideal, but if it weakens the spring long term, I can't say I care! I could've removed parts instead, but I'd only lose them!)
I also took this opportunity to improve the shutter release: the button on my R-D1 has always felt a bit "scratchy" when pressed - magnified when using a soft release.
Examining the shutter button, the problem seems to be that the lower, tubular, part is catching on the sides of the shaft in which it travels. My solution: round off the square edges of the shutter tube exit, and polish the satin-black paint on the tube to a mirror finish, using fine-grade wet-and-dry paper and metal polish. (I deliberately didn't polish the hard paint off, as soft, bare aluminium rubbing on the steel shaft could lead to the button feeling even worse over time.)
This has completely changed the feel of the shutter button: it's now as smooth as silk when pressed!
Neither of the above are major changes, but they do make the camera even more pleasant to use.