Eureka 6993 power switch will not stay on

You have a blockage somewhere either in the hose, or in the unit.

https://www.google.com/search?q=eureka+airspeed+blockages

..

The power switch cold be broken and not working.Check to see if the filter is clogged and check for a clogged hose or filter and unclog the hose and replace the filter.

I am not sure about your "Boss", but a lot of vacuums have thermal cut-off switches built into the circuit so if the machine overheats from things like clogged filters/hoses the switch kicks in and kills power. You usually can NOT reset it manually ... you just have to wait until the machine cools down.

Well documented issue, overheating, melted cheap wiring, cheap burned out switches made in China, a Dyson, it is not!

Had exactly the same problem with my upright Eureka Model 5893 bagless. Eventually, the handle would get hot, and finally it just quit. When handle was disassembled, the wires were melted and it was toast. Ordered a switch after talking to several repair men. Talked to Eureka, too, and they were absolutely no help. Cheap wiring and switch made in China. Good luck trying to find a switch. vacuum-depot.com has switches, so you might try there, but make sure you get the 3-prong switch (same switch used on Eureka's Genesis). It is Part #27871.

And lots more

https://www.google.com/search?q=Eureka+vacuum+model%232961+Won%27t+start

check for plugs, if not plugged could be a switch or a cord short.

overheat sensor is bad clean filters and check for clogs

The Motor has locked up due to over heating. Once that happens the only way to go is either replace the motor drive or get a new cleaner. Do not try and keep energizing the Vacuum as you could blow circuit-breakers or start an electrical fire.

Replace the power switch

The filter is not the reason it's not working. Take out screws and open Power Paw, remove fur from the roller brush on the right side, there is a small gap where fur winds around tightly, cut off with scissors or pull out with a small toothpick.

COUNT ME IN ON A CLASS ACTION IF ANYONE KNOWS A GOOD LAWYER.
Here's my story, posted on other solutions here, especially on the Model 5893; many people with burned wiring and switches. Major fire hazard imo! Okay, here's the skinny on my upright Eureka POS vacuum:
Had a problem with my upright Eureka Model 5893 bagless kinda starting and stopping. Eventually, the handle would get hot, and finally it just quit. When handle was disassembled, the wires were melted and it was toast. Ordered a switch after talking to several repair men. Talked to Eureka, too, and they were absolutely no help. Cheap wiring and switch made in China. Good luck trying to find a switch. vacuum-depot.com has switches, so you might try there, but make sure you get the 3-prong switch (same switch used on Eureka's Genesis). It is Part #27871.