This is just a guess. The fuse (F1) next to it would indicate that is the power input section. Any 4 terminal device near a power input is likely a bridge rectifier. Without markings on the device or service information, finding the right replacement is guess work. Installing a new one would also be guess work as you need to orient it properly. You can easily test that device. Each terminal has a diode connected between it. Testing with an ohmmeter will tell you if it is good by reading each set of terminals in both directions. One direction will be low resistance, the other will be high. If both readings are similar, it is bad. If it is bad because of LOW resistance both ways, the fuse, F1, is likely open also.
You can then read the PCB terminals to determine which are The AC inputs (they should read open) and figure out the proper orientation from the diagram and device Ohm readings.
crwdns2934105:0crwdne2934105:0
crwdns2934113:0crwdne2934113:0
crwdns2915270:0crwdne2915270:0
crwdns2889612:0crwdne2889612:0
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