fan not turning on my creda built in double oven?

the fan starts and then slows down then stops completely(clangs a bit as well), did this 2 years ago and called fitter in who replaced the fan motor, was working fine for about 1 year then has started to stop again and the oven doesn't get very hot even on 230 when the fan isn't working although the element is working as I fitted a new one even though it didn't look broke, can't afford to buy new cooker yet even though it is about 12 years old!!!
This happened the first time on Christmas day 2 yrs ago and looks like it gone again HELP!!!
CREDA EUROPA MOD NO. 48164