Air only warm

Hi, thanks in advance…
WhiteNight CL382, vented tumble dryer.
Air only getting a little warm,not hot enough to dry clothes efficiently.
– both heating elements are hot to the touch after testing
– if I take the thermostat out and run the machine with it in the cold, the air doesn’t get any hotter
– there’s enough air flow and no apparent blockage, I’ve tried with no vent pipe at all and same thing
– machine runs outside the house in an almost rain proof, definitely not airtight mini-shed, with vent pipe going out to the air

My only thought is that the switch is stuck on ‘low power’ (even though it flips) and with the outside air temp it’s not getting hot enough. Any idea how to test that? Or any other solutions?

Thanks
Kevin