Does anyone know where the usual cracking spots, or where to look for them are on a getrag case? Do I need to get it magnifluxed?

Im currently rebuiding mine, I cant find any cracks, but the more I read other posts the more I feel my symtoms would have ended up in a cracked case.
I may just be paraniod, but I just wanna be sure before I put this thing back together.
Thanks

 

A good thourough visual inspection will suffice, check the area around the Idler.

 

Maybe some fluorescent dye as used for air conditioning systems, and an ultraviolet spotlight?