Keep on keeping on Peter. Personally, I use 3M Glazing and Spot Putty. This stuff is the same as Squadron Putty but red and waaaay cheaper. Lay some tape on either side of the gap and spread this on thinly; I use a flat toothpick. Remove the tape immediately and this is where you are going to get some opinions....I use nail polish remover.... dip a Q-tip in this and remove excess putty as soon as the tape comes off. You won't need to sand the join. If the join is too big, fill with plastic sheet or stretched sprue and then putty