DJM 600 trouble

Lately, when I've been switching on my 600 prior to a mix the effects unit has remained lifeless - just like there's no power going to it. The two LED displays come on but just show dashes (---). The mixer still mixes and produces sound, but the effects unit & bpm display don't work.
If I then physically unplug the mixer, plug it back in and then switch it on the effx unit then comes back to life as if nothing had happened. Anyone had any similar trouble with theirs?
It's about 2 years old b.t.w. so I assume the warranty has expired.
Any help greatly appreciated!!