Well I did install new belts, it was 2 or 3 years back and only now I got the time to get back to the machine and try to run her.
I hope that they are the correct ones.
They are 5mm red round rubbers (both, small & large) and were purchased relaying on the store's recommendation, that got all the relevant machine info from me.
I think it was from
www.btrade.ch, though I can't remember for sure.