Interesting refurb and an amazing £75 in your pocket.
These often used to come in for repair back in the day because a rear wheel kept falling out, usually on the pedal side. A cracked chassis at the wheel arch, which gradually got worse, was the cause and a common fault on the 600 series. A new chassis was quite expensive even then.
There's an electrolux switch as found on these machines, included in the parts I'll be sending.