Emin,
Before use, cleck that the high level device/ lint filter is properly in place - it can fall off if you bump the machine when unloading.
After each job check/clean the lint filter. check that the dump valve is fully closing - if not a long-brstled brush can remove debris fron the grove which the shutter runs in.
Flush the soil tank with clean water, using a brush to release any gunge of tank walls - pay particulat attention to the area of tank the dirty water hit on the way in as you may get quite a build-up of fluff/hair at this point.
Pumping through 10 ltrs of water does sound excessive, how much flushing is sensible depends on what you have put in the tank. If you normally use an extraction detergent but have been using an acidic rinse, it would be beneficial not to flush at all.
Don't forget to check to rubber seal of the soil tank lid occasionaly, these can become damaged/detached causing partial suction loss.
John.
