Hotpoint washer/dryer sounding like a squealing car fan belt!!

I am guessing this is one for someone like Denis or Colin but anyone welcome to advise ....

I have just phoned my dad who agrees with my diagnosis of a slipping belt. He says the belt can be adjusted by altering the ratchet in the back of the machine???

Now if I have clear instructions I am ok at diy type stuff so does anyone know where siad ratchet would be. My dad has said he will come across during week and sort it but he is still recovering from heart attack and I am less than pleased with the idea of him trying to sort it so if anyone here can help it would be appreciated

Don't really want to phone repair man as he'll no doubt charge fortune for what seems a simple job and then have to come back in a fortnight to fix some other fault he has created!!!