Righteo, your problem is not exactly all that straight forward as i dont have a great deal of information to go on with regards to this type of issue and this make/ model of vendored appliance, so I will begin by explaining how the typical vacumn cleaner functions (in relation to your issue) and what can cause a fault of this kind.
The vacumn cleaner overall (unless is a liquid cleaner as well as a conventional dry suction unit) has the function of providing suction into either a chamber or bag which is either filtered or emptied, and the effects of loosing suction usually are effected by faults within filters, or directly through the motor that is normally powered through 240V~ (AC) within the UK or
115~ (AC) USA. Suction can also be lost through blocked exhaust outlets through the vacumn unit and also through any perforations or tears to a bag/ container that is used in order to maintain constant suction and storage of particles/ vacumned waste.
Now to investigate the fault you have in regards to loss of suction within your unit.
Firstly You should query the suction motor and the copper windings as these are both electronic and mechanical components that can be affected not only by general wear and tear, but also by various ingressions (such as water and liquids). Also heat can play a major role here, as motors can spin up to a large amount of revolutions per minute (RPM) and this will cause heat build up, add this to the fact that the windings inside most electric motors are made of copper, and you can quite easily discover that the motor will "burn out" as copper will break down at somewhat lower temperatures than other electronic components (this is also more likely as the casing of a DC/ AC motor is contained within a steel structure which is a good store/ conductor of heat).
The other factor that should be considered with vacummn failures is also associated with exhaust impedances. In otherwords, if outlets and filter channels are blocked, then overloads through the motor wiill be likely and the entire system may cease altogether.
In addition to this, investigations of the power supply and any power transformers within the unit should also be queried, along with any rectifiers (used for converting an AC signal to a DC signal for use with DC motors if necessary), as faults with these can occour even over short periods of time.
If queriying these components have returned no results to the fault, then there is always the option of attaing the service sheets for your appliance from the manufacturer/ vendor of your appliance. The best thing to do in this case is either to go to http://www.google.com
or to the website that is listed for your manufacturer/ vendor. Now if google if your option, then there are a few keywords which will assist in your search for your service sheets and they are to simply either type your appliance name followed by the words "service sheet" or "repair manual" In addition to this, you can always contact the manufacturer/ vendor of your appliance directly by telephone and delegate with them in order to request user manuals and servicing guidelines, and given the fact that you have a small appliance, if you mention that there is a possibility you would order any spare parts through them, then i really cannot see a reason why they would decline offering you the servicing guidelines/ manuals at a low cost.
Now there are other things here that can be investigated, but in order for me to dfo this i will need full details of your appliance model number and maufacture code, along with full details of the fault, as accurate as possible. Also photographs of either the machine or any/ all of the internal components will greatly help as direct visuals will aide not only in the identification of your make/ vendor model, but also may give a visual clue of what could be defective within your appliance (for example scortch marks on the wiring that supplies your vacumn motor etc) But any pictures supplied will need to be of a high resolution and quality.
Well I do hope that this brief explanation will provide enough information for a fixya or even a total unit overhaul in the most cost effective manner, in addition to this i do hope that i will hear from you in the somewhat near future as so i can find out more about your fault and indeed if you have managed to resolve it elsewhere (and even how this was done).
I am here most days and nights and any contact to and from me will ensure that I endeavour to resolve your technical issue in the most appropriate way for you.
In the meantime, i do hope you take care, and look forward to hearing from you soon
Here on demand for all your technical needs