Instruct: Classify a given Amazon review into positive or negative sentiment.
Query: failed just after warranty

I was generally happy with the product, although I did have to change the selectable transmission channel on occasion to eliminate static in the sound. This was not a big problem, but just after the warranty expired, the sender unit would no longer change frequency channels. It is locked on one of the four transmission channels and while the unit functions on that channel, I can no longer change to eliminate static.