Mark
Start with a clean sheet. A fizel could be anything. Presume nothing.
Listen to what the customer has to say. It may or may not make sense. Then....
Don't believe anything the customer tells you :

Do your own survey and your own tests.
Only then can you come to a worthwhile conclusion.
Safe and happy cleaning

Ken
PS If it is a sisal, or a seagrass, or a jute etc. carpet, any water based system WILL cause shrinkage, hence the need for dry compouind extraction.