My Dyson v6 vacuum has been operating intermittently for the past couple of weeks. Basically, when fully charged it operates for about 1 minute and then cuts out. When placed back onto the charger for about 30 seconds it operates again for about 3 minutes and then cuts out again and so on. I have thoroughly cleaned the device and attachments but the problem still happens. Grateful for any advise on how to sort out this problem