There's a lot of unnecessary code in each of your blocks of code:
new Scanner(System.in);
char first = response.charAt(0);
if (first == 'R')
Right = true;
else Right = false;
Why the new anonymous Scanner object before each block? The original Scanner object, stdIn, could be reused, but one isn't needed, and the anonymous Scanner object created at the start of each block is completely useless.
What purpose do the variables serve? The code in each block could be reduced to:
// check if first character is an 'R'
if ( response.charAt[0] != 'R' )
{
validCombo = false;
}
Again, take each requirement of the assignment at a time:
1. Consists of exactly nine characters.
Write code that checks the length of the input string. Valid if exactly 9 characters.
2. The character at subscripts 0 and 6 must be 'R' - to indicate turning the dial to the right.
Check that the characters at 0 and 6 are 'R' . . .
and so on. Document your code with the requirements, write the code.