brake light switch question

[hotrod351]

i just installed a rebuilt power brake booster on my wifes 70 mustang. the biggest problem i had was the stoplight switch working, it wouldnt. i installed the white plastic shim and the black plastic bushing and then the switch and the outside white plastic shim then the retaining clip but no matter what the brake light switch wouldnt work. all i could figure is that there was no movement in the rod coming out of the rear of the booster that hookks to the pin on the brake lever,, seemed that there had to be enough free play to let the booster rod push back and depress the stoplight switch. i tried everything i could think of and finally took out the bushing, that gave it enough play so when you push the pedal down it moves back and works the switch. is it that the hole in the booster rod should of been bigger to alow for enough play to push back and work the switch. what am i missing.