<sigh> another chance to take a pop at Piosneer...BUt I'll resist...You pays your dosh, etc..
As for the Numark: Generally, Numark are very helpful when it comes to spares and circuit diagrams (unlike the other oft-mentioned company)...If your mixer cost £100 or less, then £60 is poor value for a repair...eith buy the parts and do it yourself, or ditch it and buy another...However, avoid cheap mixers fo any make for anything other than bedroom use cos they will always let you down...
If you must have a budget mixer, look at Vestax or Rane or Ecler....Better ones? Allen and Heath, Tascam the better Ecler ones and the Behringer DX1000 (non of the other Behringers, though)...