My bissell deep clean steam cleaner... motor sounds like hitting against something...suddenly quite loud.

SOURCE: Hoover Steam Vac V2 Deep Cleaner leaking clean water

Fill the tank and determine if the plastic is leaking, or if the valves are leaking. if the tank is cracked, it would need replaced. There is an improved design now available.

You may cycle the valves on the bottom with the eraser end of a pencil.

SOURCE: Cleaning the bissell little green

Bissell 1425 works great, but today will not ****! Spray is fine....just no suction, even without any attatchments.

SOURCE: Bissell pro heat steam carpet cleaner, not releasing water.

That means that you need to replace the pump belt. Here is the belt you need and a manual you can view:

Bissell 7901 Belt and Manual

Testimonial: "just what I was looking for thank you"

SOURCE: ProHeat Turbo Deep Cleaner Upright Steam Vacuum: Hello, My Bissell Proheat is not spraying water, ...

Most likely the pump belt is worn and needs to be replaced. Here is the belt you need:

Bissell Proheat Pump Belt