The work needed to repair a Bissel carpet shampooer depends on the issue. If the carpet shampooer isn't spraying properly, the repair requires identifying the reason for improper spraying before fixing it.
If the Bissel carpet shampooer has a in-line filter, locate the red solution filter cap on the bottom. Use a flathead screwdriver to remove the cap. Remove the white filter, and rinse it under cold water. Reassemble the filter and cap.
Next, check the water tanks. Try lifting the two-in-one tank assembly by the handle. If it stays connected, it's properly assembled. Otherwise, press the lid and tank back together. Now check the gasket at the bottom of the two-in-one tank assembly. Ensure the gasket is present and attached facing outward. If not, either replace the gasket or reattach it as appropriate.
Check the spray; the above repairs may have solved the problem. If not, remove the tool at the end of the hose. Check to see if the hose can spray without the tool. If so, clean out the tool and reattach it. If the hose still doesn't spray, replace the tool.
If there is no spray in the hose, fill the tank with hot water and try flushing the hose by pulling the trigger. Lightly tug the hose to release any kinks. If the carpet cleaner still doesn't spray, it may need a professional repair.