Audio Research VS110 Middle transformer gets very hot the 2 sides not so is this normal

Martin Logan sl 3
just loud enough to here all the music 
about 9 o’clock on pre amp which starts out at 7 o’clock 

Thanks to all above I certainly will consider  all advice 

I have another question if you don’t mind as I am new to tubs 
the right speaker is louder than the left ( not by a crazy amount) but currently there nevertheless 
would this be an amp issue - prep amp issue  or speaker issue 

I will switch the right & left speakers to see if it a speaker issue 
but how would you distinguish between the amp & pre amp