Hotpoint Dryer CTD40G?

The dryer is constantly cutting out when drying larger items (but will still happen with smaller). It then goes onto a cool/cold cycle.

Pre Christmas I stripped the whole machine down and removed loads of damp and dry fluff from everywhere within the machine and ensured hoses were free from blockages to the rear of the water container.

This worked okay for a while. Now it's back to cutting out whilst drying for example towels. It might run for 20 minutes or so okay then start cutting out every 5 minutes after that.

It is heating up so it's not that the thermostat isn't allowing heat. But could it be that the thermostat is letting it "overheat" and cutting out?

Do I replace all thermostats or just one?

Thanks for any advice given.

Model:CTD40G
S/N: 504050478 (seems to make a difference as to what thermostat kit required)