Thanks for ur reply.
I want to make 78.6 ohm resistor. I took one 75 ohm resistor & started scrapping it till i got the value 76.8 ohms. This way i made the accurate resistors i wanted to replace the defective resistors.
the same resistor will be different ohms in different frequency
In my expierience,you can use network analyzer to measure it,and then replace the same ohms in hte same frequency.
hope that it is useful