Our carpet cleaner was no longer working well and when I checked I found that the green plastic "drive shaft" was broken. I'm pretty sure it's because I hit the low and then the thick carpet without stopping or lifting it. Without working brushes, the machine just doesn't clean well. I ordered this replacement from Revain, snapped it in and we're back to cleaning like before. I'm pretty sure this drive shaft is plastic to protect the machine, but I wish it was a little stronger. Otherwise the machine (with brushes) does above average work.