I stopped using Squadron Green long ago as in my opinion worked ok only if a new opened  tube.   I use MEK Goop made up with scrap styrene plastic and MEK as already described.  If used a very fine wire applicator (photo attached) to apply.  I also use Testor’s putty in grey tube with white letteing.  The putty is white in color, applies easily and does not shrink.  If in a hurry either of these can be set quickly with an application of CA.   Both of these old school; however, work week for me.  Another old one is to fill crack with baking soda followed application of CA.   There are many new putties on the market today, some made especially for plastic, that all work well.  Just takes time to find one you are comfortable working with.
Keep Modeling,
Lester  Breuer