Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Chain tensioner broke in after 1 month of light use

For the first month the e300 was great, then one day it stopped moving and starting making a grinding noise. I took it apart and found the chain tensioner was broken. When I went online to try to order a new one I found that everywhere I looked was sold out of that specific part - while every other part was readily available. Obviously Razor has a defective part that needs a redesign.