<< When you plug the hose into an outlet it starts for a second and then shuts
Could be an overcurrent starting problem. Start by servicing the motor unit;
oil the bearings, check/replace the brushes, clean out trapped dust bunnies and
such. Check the motor for obviously burnt windings, and bad commutator
segments. If it looks suspect, get out your parts list and check prices for
replacemnt motors. Then take it to an old fashioned motor repair shop and get
their cost estimate for repair before deciding which is most cost effective.
Switches and relays may be part of the problem and should be checked, or if the
parts cost is reasonable might be simply replaced as likely wear item.