I bought an HP-45 at a garage sale for two dollars. I inserted a good battery pack from my inventory and the display wouldn't come on. I connected a charger and the calculator works. I looked in the charger connector and saw that the spring switches that are supposed to connect the left and right terminals when a charger isn't connected aren't making contact. I tried to take the back off the calculator to see if I could repair the spring switches. I removed the screws in the battery compartment and the screws under the feet but can't get the cover off. Something near the center of the calculator seems to be holding the cover to the calculator body How do I do get the cover off?
Another question: Can I damage an HP-45 if I connect a charger without a battery pack in place?