Try to get a good quality case knife, there are a few different
types, regular knife shape, hollow ground shape, flat spoon shape,
lever type. they all have their own particular use and its just a
matter of having the right tool for the job. I have a number of case
openers, mostly by Bergeon, the common knife shape is the one I use
most and if that fails I just move on to the next type.
The thing to remember is that most case backs have a particular
place where they should be opened from and should be replaced with
the same orientation. Looking from the back of the watch there is
usually an indentation or a flange at the 1 o'clock position or else
an indentation at the 9 o'clock position, then its just a matter of
levering the back open. Things to watch out for are one piece cases
where the watch movement is removed through the front of the watch by
using an "octopus tool" to remove the glass and pulling apart the
split stem. Also some watches have the levering point between the
lugs and this you wont see unless you remove the strap first.
Refitting the back, make sure it is in the right position with the
cut out above the stem, some watches have a dot to assist alignment.
Remember if was hard getting the back off it will probably be just as
hard to refit it. The thing is to push the back on square, and not
one side first. Here is where a good case press is a godsend, it only
takes a little force to do the job. If you don't have a proper case
press try using the bottom part or your wedding band
stretcher/compressor, use a piece of leather to protect the front of
the watch where it has a flat glass and for raised glass it should
fit into the appropriate hole in the base of the wedding band
Hope this helps,
-where yet again it looks like it will be another wet Christmas.