Hi, if it's been used alot the brush or both brushes in the motor might've worn down to the cut-out plunger in the end of the brush which pops out and cuts the machine as you describe, you can pull these plungers out with pliers and refit the brushes to get you going until the new brushes arrive, £4.50 each at Spare Parts World. doesn't seem to be an overload button on these. cheers bud.
chris p duck, March 2022