If you "dom't do solder" then all of your tanks will shortly be static models. Don't waste the suppliers time and money sending them back either. You have to open them up and work on them, especially in the beginning to bring them up to minimum reliable standards.

A quick search will bring you to numerous posts on how to work on and service the airsoft unit. Quite a few on how to modify them for more power too. See my Walker BullDog build for some tips too. Mine shoots 205fps, nearly 3x more powerful then stock reliably.