I have two Ryobi string trimmers. One is fancy and has several attachments. I use it most of the time but the engine is getting tired (losing compression). The other is just a string trimmer, no attachments. I'm thinking about swapping the motor off the trimmer I don't use much (764R) to the fancier one (770R) that I use a lot. The motors (engine blocks) look identical externally but the 770R has a centrifugal clutch. The 764R has no clutch. Can anybody tell me, before I take them apart, if the engines will swap? I'm guessing the flywheels might be different because of the clutch? Are the flywheels interchangable?