Very odd mixer tap problem

[Loofah]

My kitchen mixer tap (conventional type, not disc) has started doing something odd. The hot water (it doesn't affect the cold side), when turned on and cold runs fine. Shortly after as the water heats up the flow reduces and starts to aerate the water until the flow is no more than a dribble. At the same time there is a noise, almost a screaming really, that increases in pitch.

I've taken out the hot tap section and had a look and all is fine. I've removed the main nozzle piece, ditto. So I can only think that somewhere in the mechanics something is fouled up. But what is it?!

 

[compheat]

have you noticed if when you turn the tap on that its not turning as much as the cold one to be fully open??

My guess is you need new internal section, Tap revivors cost approx £10.
not sure if the noise is caused by the same fault.

 

[Loofah]

I think there is a small difference between the two. I'll have a look tomorrow and find a new part, thanks!