my royal doulton close coupled toilet will not flush?

the toilet bowl fills with water and goes away very slow
having diconnected the cistern i have found a part
that is fitted to the bottom of the syphon with a pipe
that fits into a hole in the back of the pan with sealing washer which has gone to bits.
i assume this is the reason why there is no syphonic
action to create a flush. Is it possible to buy this part
and ware could i purchase one Thank you H.P.