Over eight years as a daily scrubber on all types of residential carpets from olefin berbers to poly Shags, my GLS used two gear sets with bushings for a total cost of about $80/repair. A few weeks back it died in the middle of a job and I thought the motor was dead, and I thought it was dead for good. I was ready to order a new one (I'll probably go with a 17" brush pro with the debris baskets if I buy new) when the local elctrical repair place called to say it was ready to pick up. It cost me $75 to have a fusable link replaced/installed or whatever.
So ... long story short ... 8 years of scrubbing residential carpet and total down time of 4 days at a total cost to repair of $235.