It took me three attempts to buy an F3 that works correctly.
The first two were jammed up , wouldn't wind on and wouldn't fire .
They both went back for a full refund despite the BS the sellers tried to give .
The third worked great . I don't know how much you paid for it , but mine cost £120 approximately.
I suspect that a full service and repair , as yours needs , would cost close to that .
So unless you got it for free , you should send it back and buy one that works 100% to start with .