If one fires a proton torpedo, one must (ordinarily) spend their target lock to do so. In spending the TL, does one still benefit from rerolling the dice of their choice? I cannot find anything that says otherwise.

In other words, I spend my TL to fire my Proton torpedo at an enemy ship. I get hit blank blank focus. Is there any rule that says I cannot re-roll the two blanks?

Because you've already spent the target lock before you rolled the dice at all, and you don't therefore have it to spend to reroll.

Contract Homing Missile, which leaves you the target lock to spend to reroll if you want.

Yeah when you spend a token, you no longer have that token to use for other effects. No matter what the token is, if something involves spending it you can't use it for something else.

But there are cases such as proton rockets where you simply need to have that token, spending it isn't mentioned, in those cases you can spend the token for an effect.

VanorDM and thespaceinvader both covered it (and it would work this way even without the FAQ), but if you want a specific rule to point to:

Q: If a player spends a target lock to perform an attack with a secondary weapon, is he also allowed to reroll his attack dice?
A: No. After spending a target lock token to attack with a secondary weapon, he no longer has that target lock to spend for rerolling.

Thanks guys! I get it now.

(And knowing is half the battle.)

If you use Redline (Punisher) you can spend the other target lock you already have on them to re-roll. (and then re-acquire both locks after the attack with FCS if you have it - and spend one during your second attack if using Cluster Missiles - and re-acquire the lock through FCS)