My niece has asked me to "fix" her newish Dysaon DC54 which seems to be
suffering from too high a pressure drop across the canister which is
triggering some sort of shut off valve in the motor unit.

It was used to clean up some plaster, whether spilled fresh or sandings
I don't know.

I'll drag a cmpressed air line out and back flush each cyclone I can see
a spout for (42) but if that fails is there a chemical that will
dissolve plaster (calcium sulphate). I don't think brick acid will work
as it is weaker than sulphuric acid that would form the sulphate from chalk.

How soluble is set plaster?

AJH