Electric Heater got some plaster and dust caught behind it

I was drilling some drywall recently and unfortunately a lot of the dust and plaster fell onto and between the gaps in my electric heater which is situated just below my television. When i switched it on it wouldnt work and then i noticed the plaster sitting behind the heater and on the wires so i hoovered up as much as i could but i can only stick the nozzle in so far so there is still a lot of dust back there.

Thing is, the second time i switched it on there was a funny smell for a minute or two but it worked fine then. But im worried that if i just use it as normal i could be damaging or overheating the internal parts and this will be dangerous and cause a fire.

Is it best to get it taken out and serviced/get all the plaster hoovered out before using it again? Thanks for reading.