plumbing problrms in a 1979 norris double wide

(kingsport tn)

do you know where i can find a diagram for the plumbing in the master bathroom my toilet is emptying into my garden tub and has been on and off from the time we purched it 10 years ago i have had numerous plumbers come in state they fixed the prob but it keeps coming back it is only in the winter in the summer every thing works great. please help!