So a friend of mine was running this combo on a U-Boat and I'm not sure what he wanted to do was legal.
Aggromech says "When attacking, after you spend a focus token, you may acquire a target lock on the defender"
The exact wording is important because here's what my friend wanted to do:
1. Focus for 2 tokens with Recon Spec
2. Roll attack dice
3. Spend a focus token solely to acquire a target lock but NOT to modify eyeballs
4. Spend target lock to re-roll blanks
5. Spend second focus to change eyes to hits
I'm 99% sure this is not allowed. Aggromech says "After you spend a focus..." which to me seems to indicate that the focus would have to be spent doing some other normal mechanic and the Aggromech would trigger as a side effect. If you could spend a focus JUST to trigger Aggromech it would be worded like Calculation: "You may spend a focus to..." So the correct way to play it would be he would have to spend the focus to change eyeballs (which can be done even with no eyes showing) and then acquire the target lock which could then be used to re-roll blanks but those blanks could not be focused even though he has a token available because he already performed that action this attack and there's the rule about abilities resolving "once per opportunity".