Anna u dont worry abt it, i think it wud b available at thakaraparambu. leave it all behind and try to contact Praveen on 2463591.he is my friend and expert in electronics as well. so no worries anna he will help u. First of all u should make sure that wether the AFT voltage from the processor to the tuner is fine or not.
I think it is a uP contolled set so u wont b able to find any presets on it. its all calibrations r digitally controlled. so u have to enter to service mode for any corrections, it is not that much easy by u without proper advice.
i think that tuner should be replaced by a proper one.if u have the old tuner part number, just walk to Echotronics, In front of SMV. High School Over Bridge and ask for Mr.Venu then say my name he could help u. so u dont try to tamber the service mode or anything it is dangerous and waste of time as well. just contact them for assistance.
Unni