As I understand it all the 1.2 or 1.3 motors are physically identical externally at least so you could upgrade if you have to replace the motor. You void the warranty if you open the motor to find out the problem so you are a bit stuffed anyway but until you do you don't know what the problems is. With respect to bike shops, I am not sure many of them would have the experience to disassemble and find the fault given that Specialized do not/can not supply parts for internal repairs on motors. I would want some confirmation that the dealer has had some training in motor repairs before letting the loose on it. Is the bike shop supporting you even though their hands are somewhat tied?