Delonghi ECAM23.450.S EX:3- Milk Frother Issue

Hi all

I've had this machine for many years and it has only been in for repair on twice, which is impressive.  However, I'm loathed to spend any more on it because of the age and so I thought I would have a go at fixing it myself.

The issue is that the water spout and milk frother is not delivering water or steam.  When you push the Cappuccino button or water delivery button, it just sits there chugging away.  The usual noise before delivery, but it doesn't deliver.  I'm guessing it's a thermostat or some kind of switch / solenoid?

Any suggestions?

Thanks in advance!