Hard to say without looking. As for as inside the bolt far better to learn how to disassemble the bolt. Not hard, German conscripts could do it and they didn't have Youtube. You'll get all kinds of opinions but I like to LIGHTLY use a synthetic grease that doesn't change viscosity with temperature in there. Lightly meaning wipe off the excess leaving a thin film. Actually that firing pin spring is so strong it's not critical.
BTW a broken spring can result in intermittent functioning but I doubt that'a the problem.
