Brighty
a bit late as you have sent it away .
My Sunbeam Vac sealer stuffed up as yours has, day before leaving on a trip, Grand father Google came good with a fix ,turns out the vacume switch internal plates get a bit of corrosion on them and will not work, the fix is to open the case , you need an anti tamper hex key set for this ( $!0 super cheap ) find the switch by following the vac line from the vac pump, desolder two pins and remove from the circuit board, on the underside is an opening that you remove a phillips screw out off ( count the turns, so it goes back to the correct spot ) flush the inside of this switch liberaly with Isocol rubbing alchohol and blow out to dry , repeat several times and then resolder back inplace .took 4 goes ( aprox an hour all up ) for mine to clean inside the switch and now works as perfectly as before .
Though in doing this, if you arnt confident about doing it, you could get an appliance service guy to do it for you .