How do you clean build up out of hose? i do not find black seal under tank,anyone have a picture of it?

If liquid is leaking from your Hoover Wind Tunnel Mach 6.9 vacuum cleaner, it could be due to a few different issues. Here are some possible causes and solutions:

1. Blockage: A blockage in the vacuum's hose or air passages can cause liquid to build up and leak out. Check the hose and air passages for any debris or blockages and remove them if necessary.
2. Damaged seal: The seal on the vacuum's dustbin or canister may be damaged, causing liquid to leak out. Inspect the seal for any damage or wear and replace it if necessary.
3. Clogged filter: A clogged filter can cause liquid to build up and leak out. Clean or replace the filter if it is dirty or clogged.
4. Faulty motor: If the vacuum's motor is faulty, it can cause liquid to leak out. Have the motor inspected by a professional and replace it if necessary.
5. Leak in the tank: If the vacuum has a tank, check if there is any leak or crack on it. If the tank is leaking, it needs to be replaced.

I'm guessing you have an F7000 series machine. You have a bad solenoid. When they go bad they don't close so all the water poors out. Take it to your local vac repair shop for the repair.

You need some inexpensive parts.

Hoover Solution Tank Valve Seal Hoover Solution Tank Valve Stem
Hoover Solution Tank Spring

Follow the link below

http://www.usavacuum.com/HOOVER-COMMERCIAL-PARTS-s/205.htm

Two checks:
(1) Is the lid sealed to the recovery tank at the black lid gasket?
(2) Is the round seal gasket in place on the suction tube, under the hood? That tubular pipe seals to the tube on the bottom of the recovery tank.

The hose leading from the tank to the sprayer head on the bottom of the unit, or the tank is not seated properly or the tank has a hole or crack

There is a black rectangular seal under the front of the tank that seals to the top of the tank lid to the suction of the cleaner be sure that the seal is there and sealing properly that should fix it. If you need to order that seal or cleaner for that machine or any other visit www.stevessewandvac.com

When you remove the dirty water tank, on the machine, there is a screen that gets clogged and will prevent good suction, is this one clean? If it is, do you feel suction at that screen, if so then there is a problem with the tank. If no suction there, then you will have to check it over for a air leak or a bad seal.

Check the seal where the tank sits on, also is the rod inside the handle moving up and down, or is it suck down pushing the reservior asm and allowing water to keep flowing. Another is there a hose off just under where the tank sits.

I have had the same problem for six months and finally found the solution.

The problem is that the air duct into the dirty water tank was blocked. The air flows up the black removeable hose, into the dirty water tank and out through the filter. With the air duct into the dirty water tank blocked, no dirt gets anywhere near the filter.

The black removeable hose is the hose in the base of Scooba that the instructions tell the user to clean after each use. Despite cleaning this hose after each use, plenty of cat hair and other dirt passed by the hose and got lodged above it on the tank side of the incoming air duct.

The air duct into the dirty water tank is formed out of the blue plastic the tank is made from. You can find it by looking to see where the black removeable hose lines up with the tank when it is placed on Scooba. It is the same diameter is a the removeable black hose so you can't miss it.

Getting the gunk out is tricky because there is a bend in the duct. I fished most of it out with my fingers and then poked a bendable plastic spoon handle to get further down the duct. I then flushed water down it and shook the tank to get more out. After cleaning, water dripped into the air vent would come out the dirty water tank drain hole with little resistance.

After cleaning the air intake duct I ran my Scooba and got dirt in the filter for the first time in months.

After further examination of the pump I re-installed it in the machine and removed the inlet hose from the mixer valve body and placed the end in a shallow pan of water. I turned the machine on and the pimp picked up the water from the pan and pumped without failure for several minutes as I had the pump output refilling the same pan.
If I take the end of the inlet hose out of the pan for only a couple of seconds, the pump loses prime and will not recover until I remove the vacuum hose from the pump. Upon replacing the vacuum hose the pump primes and begins working.
At that point I suspected an air leak at the base of the water tank or somewhere in the mixer valve assembly. I then took the hose off of the tank fitting in the base and placed the end of the hose in the pan of water. Again, the pump performed without any problem. Therefore, I assume I have an air leak at the base of the tank where the tank connects to the machine.
I will explore this further and provide you with additional info as I make progress