when standing in front of the amplifier, and it is hot on just the very far right, then that’s a problem.
the heat-sink on either side should be at just about the same temperature, when you put your hand on top of the amplifier cover.
One third of the width in for the left heatsink and on the far right, for the right heatsink.
The left heat sink is about 1/3rd of the width in, on the left side. The far left side is where the transformer is located and it will get mildly warm, but notably less warm than the two heat sinks.
You can look for images of the amplifier with the cover off, on google image search, and you will see what I mean about heatsink locations.
https://www.hifiengine.com/files/images/Yam%20M-70%20Top.preview.jpg
The front length of the power amplifier should also not get more than warm, or rather, can’t get more than just warm. The ’box’ of the heat sink area, is going to be where the heat is concentrated. (I'm calling it a box as the 'amplifier circuit proper' is in a box like configuration in this particular amplifier.)
the heat-sink on either side should be at just about the same temperature, when you put your hand on top of the amplifier cover.
One third of the width in for the left heatsink and on the far right, for the right heatsink.
The left heat sink is about 1/3rd of the width in, on the left side. The far left side is where the transformer is located and it will get mildly warm, but notably less warm than the two heat sinks.
You can look for images of the amplifier with the cover off, on google image search, and you will see what I mean about heatsink locations.
https://www.hifiengine.com/files/images/Yam%20M-70%20Top.preview.jpg
The front length of the power amplifier should also not get more than warm, or rather, can’t get more than just warm. The ’box’ of the heat sink area, is going to be where the heat is concentrated. (I'm calling it a box as the 'amplifier circuit proper' is in a box like configuration in this particular amplifier.)