I’ve had this receiver for quite a while now and it served me well but lately it started acting up where the center speaker and the subwoofer would start to drop out from time to time. The usual hit would bring it back and there was always a clicking sound when it happened. The clicking sound normally is related to electronic relays which are shown in the first picture (The blue ‘boxes’ are the relays in this case). A little bit of searching on the internet revealed that contact problems are a known problem with this receiver and resoldering the connection points of the relays fixes the problem. Once I opened up the receiver there are three relays which I suspect each controls two channels of the receiver being center and sub (and my problem area), front left and right and as last rear left and right. In order to fix the problem you will have to take the whole unit apart, if you aren’t sure you can piece it together use a digital camera or a smartphone to take some pictures before you start so you can see where all connections went. After you removed all the components and have the main PCB in front of you, you can look at the front side where the relays are and on the back which connections need your attention. Each relay has six connections and just heating them up should be enough. In my case I needed some additional tin for one of the connections, maybe this will be the case for you too. After finishing this you can assemble the unit and test the fruits of your labour. So far it is working out for my unit just fine.