In my DJ setup at home, I have a pair of Technics 1210 MK IIIs with
Ortofon Concord DJ cartridges plugged into a Pioneer DJM 600 mixer.

For some reason, the signal from the right-hand channel is louder than
the left by about 1-2dB.  I really don't know why.

I have:

o Swapped the cables over to eliminate problems with the mixer - the
right-hand signal from the deck is still louder/stronger than the left
- even when it is plugged into the left hand channel

o Purchased new styli for the Ortofon carts.  Someone in a pro audio
shop told me that the problem was most likely to be caused by the
needles wearing out.  This hasn't helped.

o Played around with the arm level on the deck - it should be horizontal anyway.

o Changed the setting of the anti-skating on the deck.  - I think they
should be set to a certain level.

$25 to the person who enlightens me and helps me solve this problem.