[Coco] Melted Keyboard Repair

[Kevin Becker]

I have a CoCo2 with the "melted" keyboard that I picked up as part of a
bundle at some point. I got an oscilloscope for Christmas so I finally
dug it back out to look into some issues it had and test out the scope.
The display is working properly now but I've discovered several of the
keys don't work.  There are several bits rattling around inside the
keyboard itself.  I wanted to take it apart to have a look but it is
welded shut with melted plastic.  

Is there a good way to open it up?  Melt the welds?  Drill them out? 
Any other repair tips?  I've heard it mentioned that CLoud9 once sold
replacement membranes but I've never seen them on the site.