Honestly, you shouldn't be force feeding at all. Make sure your new home is right and Bowser will eat, he has before even in the condition he's in. Force feeding is something that is stressfull for the animal and should be avoided unless REALLY needed. I agree with aj, give him some time. Your going to be taking better care of him then his last owner did, so Bowser will eat in time, especially if his temperatures and humidity stay right.