Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Two dead Ducks

I use 2 of these at a middle school woodshop. We have had nothing but problems with them. Now before you think it is because of the hours of use, let me explain. When they are running, they are only on for two hours 4 days a week. Within the first 2 weeks, they both died. The repair shop took their time (3 months) to fix and then they broke again a month later. Back to the shop and 4 more months! Both circuit boards went out and the linkage get very sloppy. I just had another circuit board go out this week. I wish I could replace these, any ideas?