Brother machine help

Hi guys,
I recently bought one bes-1204 and one bas-423. Both are in great shape and working. Problem is tech came and changed neddle stoppers,on one head of each machine and left instructions to finalize on the others. Now they wont work! Anybody has any experience with these ones? Any help will be much appreciated.

Sammy Vazquez

Sammy Vazquez

Did you get this problem fixed? I have single head Brother machines but I am not sure what you are talking about. If you turn off the other heads does it work?