It is an Atco/qualcast motor as they were and still are made in-house at Stowmarket.
I don't recognise the model PS35s. The Classic electric range didn't start production until 1995, so I can't be a Classic electric punch of 1993 vintage. If it is the previous model known as the Punch EP35S, then as with pretty much all Qualcast motors you won't get brushes as they are a sealed for life motor. Unfortunatly new motors are now obsolete, so it's a case of obtaining a second-hand mower and robbing the motor or ringing around dealers to see whether they have any old stock on their shelves (unlikely). The last price I have for one is £42.00 plus vat
pleasant, August 2008