Grundig RR315 no fast forward/reverse but output fixed

Hello I have a cassette/radio Grundig RR315 and it had no cassette output but thanks to the tip to put WD40 on the switch, I sprayed selection switch and now there is cassette sound output although not sure if it is playing a fraction slow ! Now I don't have fast forward or reverse back but I will see if a belt has come off as the white opaque wheel moves across mechanically to touch the other wheels, which one depends on the direction fast forward or fast rewind but nothing happens, the wheels stop turning. Any tips thanks in advance