I agree, the plastic "bait holder" is too slick, and it is therefore impossible to set the arm where it will stay. I have been using the sticky traps. The little furry critters step up on the trap and can't get away. You have to throw the trap out in the woods somewhere and let the little fellow get eaten by larger critters who also get stuck to the trap. I hate to do that and let the little fellows fend for themselves, but it is better than them getting into the car, etc. I also stuff very fine steel wool up into the A pillar so they can't get up into the header panel and piss on everything up there which subsequently rusts out the panel.
This has my best laugh all year. I like to make a sporting game out of it and try to catch them in traps with no bait.
This is the one I use. Just enough water in the bottom so they cant keep their head above the water. Perfect. Can catch dozens. And if its in a cold climate a touch of antifreeze in the water helps.
Getting back to the squirrel bird feeder zapper I always wanted to rig up a old dog shock collar to the feeder, so I could sit in my chair looking out at the feeder and zap them when I see them on the feeder.