just brought a sony cfs 9000 in good condition from uk ebay it needs belts are they hard or easy to change any info please

I've changed belts in the CFS9900, I guess the same mecha. You dont need to worry a lot.
Take the front apart (be carefull with cass door, it's enganged to the mecha, not to the front case. Open the door an then remove the the front.
Take the mecha aparte (only four front screws ...). The mecha has off board conector for all the wires, so it's easy to work with it.

Mecha take 3 belts, one main flat belt for the two flywheels (two, since mine is autoreverse). another goes to the motor too. The third I'm not sure ...

You will need to work a little to put belts
because motor pulley goes inside the mecha, but you will manage ...