whats the make and model of the strike?
Make and model of the power supply?
Did you try taking the strike apart to see if a coil is burnt or something mechanical?
Could it be a dual voltage strike and your using the 12v harness with 24v power supply?
Just a shot in the dark, but do you have enough current from your power supply? sounds like if it's only dipping down to 23.5V you probably have enough but when its not working try firing it off a couple SLA batteries and see if it releases, if it does I would suspect current