Hi Diane,
What do you mean by a bit of a tune up?
Provided the bags are no more than 2/3 full and the hoses and filtres are clear they should not splutter. The brushes may need changing depending how long the vacuums have run for, but you would need to contact Numatic with the serial number/model of the machine because they have used different motors over the years.
Their tech support has been quite friendly and helpful in the past and will advise you further. Consider getting a PAT test if you do any electrical work youself, otherwise you may invalidate your insurance.
Good luck
Mike