My new JTM45 acts strange on the input side. The two top inputs are supposed to be normal sensitivity and the two bottom ones lower sensitivity. On mine the two top inputs are just lower level, less treble versions of the bottom two inputs. Just sounding dull and lower level. Also, jumping the 1&2 inputs does not work. When jumping, channel 1 takes over and channel 2 almost does not add anything (just a tad) even when the normal loudness level is set to max (and the high treble loudness level is still low). What can I do?