The newest generation of Tranformers toys come with a disclaimer; the toys are designed to pull apart when excessive force is used.
What this literally translates into is 'Parental units, be ready to put Megatron's arm back on several times a day.'
During J's learning phase of getting a new one, I have to put some piece or limb on once an hour or so. A day or two afterwards we nip that in the bud by offering one free fix a day. Afterwards, we fix the limbless Autobot or Decepticon and keep him for the rest of the day. It teaches him to take care of what he's got.
The new issues is getting help for that fix. He knows I'll do it, but he can't pull himself away from what he's doing to come get the help...to the point of tears. "Why Daddy?! Why won't you come fix Optimus Prime?! I want you to do it now!"
"Buddy, does the mechanic come to our house to fix my car?"
"No..." he says as he's processing it.
"Do the nice checkout people bring us our groceries from the grocery store?"
"It is impolite for you to demand something when you need help...especially if you're the one that caused the problem."
"But Dad! Brawl's leg fell off all by itself."
"Do you want to go into timeout for lying to me?"
"So when you want help, it is rude for you to make me stop what I'm doing to help you. I want qand will help you, but you've got to bring Starscream to me. Do you understand?"
I then proceeded to put Megatron's arm on backwards and break and fix him again.