That would be a "Celebrity 2 Knobs" pre-amp as identified here. Removal is simple. As you say, a putty knife to pull the volume and tone knobs up. Sometimes they're really tight so you'll probably want to use a towel to protect the finish and a plastic spatula as opposed to a metal one. I don't think there are any micro screws holding the knobs in place (unless they've been replaced with an after market  knob). Once the knobs are removed you'll see the bolts holding each pot in place. Loosen those and the preamp should come loose. Good luck!