RF modulator with no sound to the out

Hello
I bought RF modulator (Mercury RF modulator) to convert Scart to Rf. The video works fine but there is no sound. I think that the problem is with Pal. The modulator that i bough is from United Kingdom. The PAL in UK is PAL I but in Cyprus is PAL G. Does anyone know how i can fix the modulator and work from PAL I to PAL G? Does anyone know if i change the crystal in the modulator the sound will work?

PAL I use 6MHz audio carrier offset, when PAL G use 5.5MHz.

Broadcast television systems - Wikipedia, the free encyclopedia

In your module if the audio sub-carrier oscillator use a 6MHz crystal, have to replace it with a 5.5MHz crystal.
If is using just an LC oscillator, tune its oscillating frequency (replacing L or C) to the desired one. You need a simple frequency counter for this.

Thanks vfone for the help. The crystal of the modulator have this number (J04-000044). I am not sure about the frequency that it work but maybe its 6 MHZ. So i will try to find a crystal 5.5MHZ to replace it