Perhaps you have used the wrong sand or it is still blowing old sand out of the pipes.
This sounds as thought the laterals in your sand filter are worn. Laterals are horizontal spokes at the bottom of your sand filter with tiny holes in them that let water through but not sand. After a time the holes get enlarged and start allowing sand through and back into the pool
Hepa vasuum cleaners have a filter that removes particles from the air that is dicharged by the machine. This filter needs to be replaced unless it is washable.
Most vacums need to be replaced every 20-30 uses.
It has been awhile since I owned a Chevy truck, but I seem to remember it was something to do with the vacuum hose or filter getting clogged with dirt. If you wait a few minutes, it should start back up. But, it is a faulty vacuum (filter), and needs to be replaced.
A sand filter has laterals (plastic tubes with holes in them) in the bottom, covered with a foot or more of sand of a particular size grain. Pool water is flowed onto the top of the sand and vacuum pressure draws the water through the sand. The particles in the water are trapped in the upper level of the sand and the clean water flows through the laterals and back to the pool. As the dirt builds up on the top of the sand (the schmutzdeck) the filter actually cleans better. Once the dirt layer is thick enough to impede the flow of water, you have to remove it by backwashing. You do not want to backwash too often or you will lose the efficacy of the filter. Be sure to shut off the pump before you move the lever to backwash or you WILL crack the laterals - requiring a very expensive repair.
Either your filter needs to be cleaned or replaced.
could be a vacuum leak
The transistor replaced the vacuum tube, allowing radios to get much smaller and portable.
Dirty air filter, Tune up, Vacuum leaks,
Vacuum leak or bad vacuum booster Check to see if you are getting vacuum to it
Most likely the filter. i would check the fingers inside the filter for tears.
The filter in a vacuum cleaner separates dust from air. Air is allowed to pass through whereas dust is trapped by the filter and caught in the bag/cylinder of the vacuum cleaner.