A direct short is usually shown as a burned spot around the part that shorted and will most likely smell really bad. Remove the board and examine it from both sides for the burned spot...if you still can't find it sniff the board and it will give you a general location as to what may have been shorted....as sometimes a chip may short under itself and will not show...but the smell all ways gives it up. Look for an expanded top on the can filters also...they should be flat on the top and not rounded.

You can't check chips and transistors while they are on the board...so again as with S-n-M asked how far are you going to go and at what cost of labor hours. To hunt down a short and spend the time to repair it and all that usually costs two or three times what it would to buy a new board....on top of that, my experience has shown that repaired boards just do not last that long to begin with so you might end up with a mad customer if he pays for repairs and something else shorts out in a week or two!