Traveller belt tensioner failure

I've seen similar on the Traveller. Is it making a squealing noise, especially on startup or when the AC kicks on? The idler pulley (a grooved wheel that guides the belt) might be misaligned, causing the belt to slip and the handover to fail. That's my first thought, anyway.

No squealing noise. Just the belt handover failure. Could still be a misaligned idler pulley, even without noise?

While engine noise like belt squeal is a common symptom, a misaligned pulley can still cause belt issues without the noise. The lack of noise might indicate a more subtle misalignment or a different issue altogether. Given the complexity of the belt system, I would recommend a qualified workshop check it.

Thanks. Workshop confirmed: defective belt tensioner. Repair cost: 455€. Replaced and all good.