Posted for "George Braly" <gwbraly@gami.com>:

 
 Eugene,
 
 Ah... I wouldn't do THAT.
 
 Effectively,  you end up insulating   one-half of each of two fins, and, in
effect,  you have just, effectively,  cut off one cooling fin in the affected
area, which is already under-cooled, by definition.
 
 You need to do the "box-in" pieces so that air can flow around the outside of
each of the outside fins.
 
 The way we do these is to start out with heavy construction paper (I use file
folders) and cut them up into shapes and folds and tape them together until I
get a good "fit".
 
 Then I unfold them in an organized way and use a little 3-D imagination to
figure out how to bend up aluminum parts and rivet them together.
 
 It takes some time.  You will build a lot of aluminum parts that you throw
away,  but you will get better at it, rapidly.
 
 Regards,  George
 

"""
 George, Walter, anyone else - I looked at making the necessary mods using
 aluminum brackets and the attachments are, as you know, very difficult. How
 about using fiberglass soaked in thinned high temp RTV (Bill Hannahan's
 idea) and bonding the sheet to the fin outer surfaces with unthinned high
 temp RTV?  This is what I had done the mods with before and I had to cut the
 sheets out with a knife to remove them, no way would they come out by
 grabbing the soaked fiberglass with pliers and pulling!
"""